Credit Acceptance Corporation Calls me 10 times a day harrassing me at home and at work! Detroit Southfield Michigan

I have poor credit due to a divorce I went through and I am raising 3 kids on my own with no child support. Meaning my credit was ruined because I couldn't afford to pay everything I owed. That's my own fault I know. However, Credit Acceptance Corp. makes my life hell every month. I always send my payment before it's due but it just takes it awhile to get there. My payment is due the 17th each month. If they don't have it in their hands by the 17th they start calling and not only that but they are so rude and unprofessional! They argue with me, they try to say I owe a late fee when I don't. They never speak good english so I have trouble understanding them. I always end up hanging up on them. Most of the time I just don't answer the phone. They have called me at work and I have told them not to anymore.
I will never do business with them again! And I would tell anyone else to stay far away from them!! I don't know what to do about it other than maybe change my phone #. Any suggestions?

Catellis
Springdale, Arkansas
U.S.A.