This sounds like a violation of the FDCPA, seehttp://www.ftc.gov/os/statutes/fdcpa/fdcpact.shtm
§ 806. Harassment or abuse [15 USC 1692d]
A debt collector may not engage in any conduct the natural consequence of which is to harass, oppress, or abuse any person in connection with the collection of a debt. Without limiting the general application of the foregoing, the following conduct is a violation of this section:
(5) Causing a telephone to ring or engaging any person in telephone conversation repeatedly or continuously with intent to annoy, abuse, or harass
any person at the called number.
An oral contract that takes over a year to perform must be in writing, seehttp://law.justia.com/codes/texas/2005/bc/003.00.000026.00.html
They have the burden of proof to show that there was a contract, and what the terms of the contract were.
From your description, it is possible that there was an oral month to month agreement, which can be canceled by either party by giving one month advance notice.
You can get a free consultation from some of the FDCPA lawyers listed by location athttp://lawyers.findlaw.com/lawyer/practicestate/Debtor_Creditor/Texas
There is a fairly detailed summary of the FDCPA posted athttp://www.expertlaw.com/library/consumer/fair_debt_collection.html
Within five days of their first contact with you, the debt collector must send you a written notice telling you:
How much money you reportedly owe;
The name of the creditor to whom the debt is owed;
That unless you, within thirty days after receipt of the notice, dispute the validity of the debt or any portion thereof, the debt will be assumed valid by the debt collector;
That if you dispute the debt in full or in part within that thirty day period, the debt collector will obtain verification of the debt and mail it to the consumer;
Please follow up on this with a local attorney. The contract itself sounds uncertain, and in my opinion, the collection agency is violating the FDCPA.
I hope this information is helpful.