Can I achieve point-to-point QoS without implementing MPLS?

I think I made a huge mistake entering into a quasi managed IPT service. My Data Network Service Company is hosting a Cisco UC 500 system for us at their co-location at Terramark. They sold us the phones. We have 6 different office locations where we have different service providers due to contract obligations. We are running 10GB Metro Ethernet between our co-location at Telefonica and two of our offices. We have an AT&T Business class DSL at one location, a cBeyond T1 at one location and Paetec T1 at two other locations (MPLS with the Metro-E locations) and soft phones running on remote locations over a minimum of Business class DSL. Further, we are running all our calls through the Paetec SIP trunks. Now everything is good at this point because I am aware that I may have problems and issues with dropped calls, jitter etc, and particular in the locations operating over Business class DSL as QoS cannot be guaranteed at those locations, correct? Well, the main problem is that we are having constantly dropped calls where the UCM goes down and resets itself, voices fading in and out, e.g. one person is speaking and then all of a sudden the voice disappears and the line goes silent and then re-appears again 10-20 sec's later. In terms of the dropped calls, I realize that when the internet connection drops it will make the UCM or local handsets reset themselves. What I don't understand is why we are having the fading in an out (Jitters) on the calls? I have asked our service company to explain why this is happening and exactly where the problem is located. They cannot explain this to me or I am simply not clever enough to comprehend what they are telling me… …They say that the Jittery (or “fading”) in and out of voice calls are caused by the inability to establish Quality of Service (QoS) over an internet VPN tunnel. The Internet circuits like those found between our offices and our NAP at Telefonica as well as their NAP at Terramark are not private circuits and do not support QoS due the multiple ‘hops’ typical in internet traffic. They say they have conducted bandwidth testing between these sites and have determined inconsistency in packet delivery. Therefore, without QoS they won't be able to control packet delivery on the network and guarantee the reliability of calls but suggesting that if I spend another $20,000-30,000 to upgrade our network to full MPLS for them to be able to provide point-to-point QoS everything will be just fine. I am just a little weary right now as they should have provided these recommendations from the start. Here are their proposed recommendations: They are recommending an upgrade (or move) to the more stable MPLS (Metro-E) voice/data transport in which QoS can be leveraged and maintained to deliver the consistent quality voice service required by us. Without this change request, the service company will not be able to continue providing IPT Managed Support beyond the next 30 days. Cost to implement changes: I have been presented with a couple of options that they say would significantly improve the stability of our LAN, WAN, and overall voice network. Option #1: This option would require the SP’s and our networks to be connected via private Metro-E. It would also require the remaining offices not on MPLS to be added to the MPLS network. • Estimated Monthly reoccurring cost - $1,600.00 • Estimated Hardware cost - $12,278.00 • Estimated Implementation cost of - $17,600.00 Option #2 - This option would move our infrastructure from Telefonica to Terremark and cross-connect it to the SP network. It will also require all our offices to be on a MPLS circuit. • Estimated Monthly reoccurring cost - $1,400.00 (excluding cross-connect charge) • Estimated Hardware cost - $12,278.00 • Estimated Implementation cost of - $23,500.00 Option #3 - We can purchase a CISCO Call Manager express and implement an in-house IPT Solution. We will lose some functions of the phone system we currently have like (Presence and Email to Voicemail), but our phone system would reside locally. The one-time equipment costs would be higher on this option, however the monthly recurring would decrease because the SP would no longer be hosting IT phone services. • Estimated Monthly reoccurring cost - $800.00 • Estimated Hardware cost - $21,658.00 • Estimated Implementation cost of - $ 26,600.00 Is all this reasonable? Is there any way to alleviate these problems without implementing full MPLS? Can I add a redundancy DSL circuit at each office location to avoid the dropped calls? Where is my weakest point in the architecture? Is the voice fading or jitter a bandwidth problem alone? What can I do to minimize our cost but solve the call issues we are having while minimizing the interruption? In the beginning the service company sold us on a very basic system that would cater for our requirements and provide a reliable service without dropped calls and stabile conversations, without implementing MPLS bar the DSL locations. In that scenario VOIP was the way to go and I would save lots of money on a monthly basis and the ROI was justified. Not so much anymore based on the new parameters proposed by our SP. Apologies for the long explanation but I thought you may need some background to the problems I am having…I am desperate for some help and I am grateful for all the assistance I can get!