MTN Billed with the prevous Contract after upgrade

I have already logged a Complaint with REF REQ:*** .I need to know why MTN billed me with the previous Contract after I upgraded in October 22nd.<br> <br> I still do not understand where the Outstanding balance of R2306.38 is coming from Let me repeat the questions that I have been asking for 4 weeks. They promised that they will refund me and deposit the money on my bank account, now they tell me credit of R795.00 was passed on your MTN sp account and was subtracted from my outstanding balance of R2306.38 leaving your outstanding balance at R1511.29.<br> <br> 1.Why was I billed with the previous Contract and yet I upgraded on October 22nd <br> 2.The previous Contract had a Soft Lock Cal limit, which I have already send the proof to MTN, as well as my upgrade Contract when they decide to charge me with the previous contract, why didn't you utilise it?<br> 3.How come I have Outstanding balance of R2306.38 and yet I upgraded to My Choice R50 on the 22nd October?<br>