Stalling Tactics

I upgraded my contract on the 24th of November 2017 at the MTN store in the Cascades Mall in Pietermaritzburg. I did not take delivery of the phone as they didnt have stock however, on the 25th i called in and cancelled my upgrade and the store manager said it will be done. On the 30th i received a delivery with the new phone but as i cancelled the upgrade i did not accept the package. I then called the store and they are saying that i have to wait 7 to 14 days. I called the MTN service centre and they informed me that there shouldnt be such a waiting period if i am sure i really do want to cancel and I AM REALLY SURE I DO WANT TO CANCEL.

I would like my upgrade cancelled with immediate effect and i would also like my number to be put onto prepaid.