MTN Gateway a nightmare

I am extremely unhappy about the service that I received at Gateway MTN. On 11 Oct I was told that I could upgrade my cellphone contract at no additional cost and that my new iPhone 15 would be be on future dated contract meaning that I would only be liable to pay for this phone in dec when the contract for that phone only commenced. I was told that I would continue to pay the old rate until December. On the 31 Oct I was shocked to have been billed for my old contract and the upgraded contract therefore being billed for 2 contracts at a total of R2090 instead of R1030. This is completely unacceptable. No one at the Gateway MTN is offering me any assistance and I am now really disappointed by the service I received at this branch of MTN. The sales person refuses to take my calls or answer my messages to her. I even have her written messages to me confirming that I will only be billed for the new contract in December. The salesperson ****. Horrible business practices from the MTN Gateway branch. Don’t do any business with them.