Wireless fee charged on returned receiver

I had 3 wireless receivers until my $10 promo for one of them expired.  Sent it back in July 2017.  Noticed on my last bill that I have 3 wireless charges.  Called to demand the charge be changed and my mkney refunded for the past 6 months since this charge has been ongoing.  Talked to 3 different people, and gave up 3 hours only to be told that from now on I will get a credit of $10 on my bill.  I explained that I still need a refund for my past charges and was told their was nothing I can do.  I HIGHLY recommend not using ATT. [Per Guidelines:  Keep it Relevant and Appropriate]. {Inappropriate content removed} Not my first major issue with the TV side of things.  Give me my money, or I go to Xfinity.