***** on Cheque Account

I made a payment for my DSTV in December 2022 which I did on my App which went through and my Dstv account was credited with the amount and I was left with just above 6K in my account NOW in February 2023 the bank debit my account for the same amount I paid in December 2022 and claimed that there system had an error for that period and my money did not went through WHERE is my money for that transaction because it went out, and Multichoice never informed me that my account was in arrears and never switched off my service. I logged a complaint and I am still waiting for someone at FNB to get back to me. Nothing is happening and my account is NOW in a minus R938. 00,how did it get there.