Poor service

On the 24th August 2018 I made a lay bye account which i put a deposit of R200.00 instead of the +-R122. 00 the cashier asked for.. End of the month i.e.August I went to the shop to pay the balance on the laybye the cashier who helped me wanted me to pay extra money because on the receipt she said I made a deposit of +-R12200. 00 which I questioned and she called her supervisor who promised me they are going to do the investigation and they will call me back.The call I received was when they told me that the lady who helped me was back from her days off and they will call and give me the feedback from their investigation. To date I haven't receive any calls from them. I'm really sad?