There are essentially 3 requirements in order to get the 7.1-15mbps tier DSL Service:
1). Verizlon has to offer it in your area (requires ADSL2+, which some Central Offices (CO) may not have).
2). Verizon needs 'backhaul' capacity in the CO. Your 15mpbs service isn't worth much if is there is no available bandwidth between the Central Office and the Internet has little or no additional capacity
3). You must be physically near the CO. The length of the copper pair connecting you to the CO is limited to something just over 1 mile IIRC. The closer you are to the limit, the closer you will be to the lower end of the tier (7.1mbps).
It's the same plan as the 3Mbps and the 7Mbps speeds under Verizon's new pricing structure. If you believe you should be able to get 10-15Mbps, it might be a good idea to provide your Transceiver Statistics so that we can at least see an estimate of the line length and quality. If you want to do this, tell us which modem you have if you don't know how to get them.