Billing two number for a single contract

In September 2015 I went to the MTN Alberton Mall branch to app**** for a Sony Experia M4 Aqua on a MTNChoice 100 contract. I requested that the pre-paid sim (***8562) I already had should be used for the contract being app**** for. I informed that they were unable to do the conversion on the sim because the pre-paid sim was previously used for another contract user. It was mutually agreed by the Alberton branch manager, Mbalani, and myself, that they issue a new sim (***4223) with the contract. <br> I discovered on the MTN Active portal that both these numbers are linked to my account as individual active contracts and I can therefore only assume that I am being charged for both. If I have to venture a guess I would assume that the request that the Alberton branch processed to convert the (****8562) sim was never withdrawn and they eventually were able to complete the conversion from pre-paid to contract. I am at a loss though as to how they have linked this as an additional contract to my account. I would like this rectified and have the (***8562) sim deactivated and any costs incurred must be reversed on my account.<br> I called MTN and was advised to submit an affidavit for *****???<br>