In regards to a refund

In Feb 2017 I called ATT to set up internet service.  During that time the salesman offered me a Samsung Tablet and stated I would only have to pay $1.00 for the tablet.  I accepted the offer and the salesman advised he would take $1.07 from my debit card.  Later on I found out that the salesman had not only set up the internet service at the wrong address but he had also taken an additional $100 from my debit card. After several days of being on the phone with customer service they finally advised me 3 days later that my service had been cancelled and that I would need to contact the wireless dept to cancel the service for the tablet which by the way was sent to the wrong address and I never received.  I contacted wireless and they advised a refund check for the $100 would be sent to my address. It has been SIX MONTHS and I have to receive that refund after several calls to your service center.  The customer service representatives are clue less on who to transfer a customer to in regards to a refund and THIS HAS BEEN A WILD GOOSE CHASE for me.  Its very frustrating and I'm very disappointed in ATT for this.  How can we resolve this problem?