Proven lack of signal at the registered service address generally is acceptable grounds for recision of contract, provided the issue is raised in timely manner from date of contract. Exact no-penalty-cancellation terms vary, generally ranging from a week to 30 days. The specifics will be in the contract you should have read before signing. If your situation falls outside of the time limit, likely the only way out is to pay the penalty.
BTW ... did you see my
Reply to your earlier post? The problem is not with the performance of the hardware or of the service provider; the problem is that the hardware and service provider's capabilities, however adequate they may be for other folks in other situations, do not satisfy the requirements of your particular and individual situation. Its pretty much up to you to make the right choices.