MTN Poor Customer Service

A laptop and router was delivered to me in April 2022. I was not expecting any delivery as I did not take a new contract. The courier said I had to receive same so I did. I open the package and returned it the next day to MTN pavilion. To date I am being charges for same. I have been in constant contact with Mondo and MTN with no feedback. My invoice for Oct shows that I will be debited R10k for cancellation for something I did not take out. I have made so many calls querying this and get no help. I am terribly stressed as this is a big amount to go of my account and this means i will be put in a financial predicament.