Drivetime has harrassing and threatening collection practices, Dallas, Texas

Purchased a vehicle one yr ago. Have asked for, and promised, a payment date change due to the fact that I am on disabilty and only get paid once a month. Every month, "you qualify, give us a call". I have left numerous messages and emails and to date nothing has been done. Now I get, your payment must be current before we can do anything. I bring my payment current and nothing happens.
Two weeks after I bought the car, the timeing belt broke; not covered under their piece of crap service contract. A month later, I noticed the windshield wiper motor wasn't working and the airbag light was on. Spent $500.oo and the car needs another $600.00 worth of work. None of this is covered. Thier SC is totally useless!
In the meantime, they call 8-10 times per day. When they call my cell phone, they leave the line open and all you can hear is people talking in the background. They do not leave a message but purposely run up minutes on the cell! They are fully aware of my heart condition but I feel they continue to harrass me versus help me to try to intimidate me. This is causing additional problems with my health and they don't give a da**!
For the record. I spent over 30 yrs in the Automobile industry. This is the worst company I have ever dealt with. They are truly a rip off and unprofessional, in my opinion.