Requires a negative rating - Appalling service from the credit card division

I sincerely wish I could give a negative rating. In April they decreased my credit card limit because I missed a payment on an account 4 years ago - Before i even had a credit card with them. They also cannot tel me which account they are referencing to but will get back to me. Which they still haven't. They ignore my messages I get transferred back and forth. I was promised they would fix this somewhere in May and guess what still nothing. They have damaged my credit rating FOR NO ****** REASON!!