Incorrect billing for contract which ended

Vodacom simply cannot get it right and they don’t honor call backs! I took out new contract 21 January 2021. Was first invoiced for handset on my February 2021 invoice. Since this was a 36 month contract my last handset installment should have been January 2024. However, Vodacom still debited my account for February 2024 and March 2024. So far Vodacom have credited my account for the month of March 2024, but I am still struggling with them to credit me for the month of February 2024. It seems that Vodacom’s system is flawed. I wonder how many other people don’t realize that they are still being charged for handset installments long after their contracts ended.

Vodacom here is the mathematics which you seem to be unable to do:

Month 1 Feb-21 Month 2 Mar-21 Month 3 Apr-21 Month 4 May-21 Month 5 Jun-21 Month 6 Jul-21 Month 7 Aug-21 Month 8 Sep-21 Month 9 Oct-21 Month 10 Nov-21 Month 11 Dec-21 Month 12 Jan-22 Month 13 Feb-22 Month 14 Mar-22 Month 15 Apr-22 Month 16 May-22 Month 17 Jun-22 Month 18 Jul-22 Month 19 Aug-22 Month 20 Sep-22 Month 21 Oct-22 Month 22 Nov-22 Month 23 Dec-22 Month 24 Jan-23 Month 25 Feb-23 Month 26 Mar-23 Month 27 Apr-23 Month 28 May-23 Month 29 Jun-23 Month 30 Jul-23 Month 31 Aug-23 Month 32 Sep-23 Month 33 Oct-23 Month 34 Nov-23 Month 35 Dec-23 Month 36 Jan-24 Month 37 Feb-24 Month 38 Mar-24