Horrific experience

Truworths is slowing becoming my worst nightmare. On 15/12/2021 I made a purchase on my Account. One my items purchased was a dress costing R440 and I had as R125 voucher so I paid R315 for that particular dress. The dress in question did not fit so I went back to one of your stores to exchange it. My credit available after the purchase on 15/12/2021 was R3717. On the day I returned to the store to exchange the dress the credit available was R3592 which I only realized after leaving the store. R3592 credit means that when I exchanged the dress the cashier who assisted me did not account for the R125 discount/voucher on my initial purchase therefore my available balance/credit became R125 less than it shoul have been. Earlier this month I went to your Truworths store in Sandton. I explained my issue and gave them receipts as proof. They called head office and I was told that the issue would be sorted and my available credit would be amended accordingly on my next statement. To my horror, today I receive an SM saying my available credit is R3067, meaning that it is now R650 less than it should be. What the hell is going on there with your accounts/finance department? This is a load of ******* you are throwing at me, considering that I have never ever missed even one payment on that account and worse I am on the 6 months interest free option. I want this mess fixed today and my available credit on that account restored to R3717 and some cents. You guys are too quick to send statements with payment due as well as the due date but your service is absolute *******. It has been almost a month and instead of a solution you come back with even more issues adding to my initial issue distress.