4th time trying to resolve overpayment issue and charges for services not received

Aug 15 paid $212.13 for Aug-Sept service. Cancelled TV service Aug 30. Monthly bill reduced to $75.09

My math= $212.13-$75.09 should leave an overpayment of $130

This overpayment should cover Sept 15 bill of $75 and $45 of the Oct bill.

I received a bill for $155 for Sept and Oct.....where is the $130 overpayment????

Also, I should have a refund of $184 for service:

Latino channel not requested form Nov 24  thru Aug  10 months @ $10.00 a month = $ $100

equipment rental for returned items Dec24 thru Aug 25  9 months @ $12.00 a month = $84

Check was supposed to be "in the mail"   3 weeks ago, according to the 3rd agent.

I have tried to use assistance agents and get the same run-around..."we have noted your account", "new bill will be issued within 24 hours"...No help at all. The only thing they want to do is sell me more service.

Why would I WANT more, when you can't resolve the current issues???