Final Letter of Demand Incorrectly Allocated

i had a fibre line with Cell c that i settled and closed in September 2021, on the 31st of December i received a Final letter of demand from Cell C stating i owe R1249.16, out of panic i paid in that money into Cell C, i then called in to find out if the funds have been received and why i was notified about this amount that is in areas earlier, the consultant couldn't explain and went as far as telling me that i don't owe Cell C and the letter of demand was incorrectly allocated to me. i then logged a case for a Paid up letter, case no: ***. i also logged a case for a Refund to be paid ***, non of these requests have been attended to and it been over a week and i was informed that the turnaround time is 24-48 hours.