MTN Charging for cancel contract for months

I intended to take out a contract at MTN St Georges Mall branch Cape Town in August 2019 to get a device for a family member. I requested the process gets fast tracked as it was for my family members birthday, and the process did go quick however it was loaded under the incorrect deal, I wanted the R99 package but it was loaded under the R159 package. The sales assistant explained to me that canceling/changing the package could take time and I realised I would not have the device by the desired day or on the desired package, I decided to cancel everything. Keep in mind I am an existing MTN customer taking out a new package, I did not sign any documents or agreements for this device. At the end of August I got charged for this contract of which I never received the device or sim card. I went to the store to query and the sales consultant was helpful but at the end of September I got charged again for this contract. The same thing happened from August 2019 until January 2020 and to this day I am being charged for a device and sim which I did not receive. I am horrified at how MTN can do this, surely it can not be legal to charge me for something I did not sign for and never received? How long does it take to cancel something? HELP!!!