No credit card required
Browse credit cards from a variety of issuers to see if there's a better card for you.
First, you aren't required to provide a fax number. Law says they have to mail it.
http://www.ftc.gov/os/statutes/fdcpa/fdcpact.htm#809
(b) If the consumer notifies the debt collector in writing within the thirty-day period described in subsection (a) that the debt, or any portion thereof, is disputed, or that the consumer requests the name and address of the original creditor, the debt collector shall cease collection of the debt, or any disputed portion thereof, until the debt collector obtains verification of the debt or any copy of a judgment, or the name and address of the original creditor, and a copy of such verification or judgment, or name and address of the original creditor, is mailed to the consumer by the debt collector.
Calling you is an 809(b) violation. Some Districts and Circuits have ruled that ANY written communication which isn't verification is a violation.
You're in Texas, right kims? You can record and you don't have to tell them.
http://www.rcfp.org/taping/states/texas.html
If you have Caller ID, snap a picture of the Caller ID unit showing the number, date and time.
If you sent two DV letters CMRRR, and you saved the documentation, then I'd say you've got them in violation.