Cox Communications AMRA- COLLECTIONS REFUSAL TO REFUND OVER PAYMENT internet, Rhode Island

I am a widow on a fixed income and trying to get a refund check from Cox communications, because they were paid for three months instead of one by my bank. The bank has sent them proof of over payment and all other other info they'd ask for, Cox still refuses to send me the check! In their records they have the information that I have a CREDIT DUE. Can any one help me? I'm paying overdraft fees because of this and I can not afford them! Yes I am over the age of 13, I'm a Senior Citizen.  I had to speak to 4 people before I was transferred to the correct department, then I was on hold for over an hour before I spoke to anyone (and it was not a supervisor as I requested)