MTN DIRECT WRONG BILLING

I upgraded my contract in May 2021, after I received an email from MTN to do so. The lady at MTN Direct advises me that as my contract is only due to end in August 2021, I will be billed for the handset fee for the remainder of the contract, whics is three months. I would then only start paying the full R549 for my new contract. The amount she gave me was R444 for the old one, R129 for the handset fee on the new contract, and another R129 for my router, which then totals R702. So imagine my complete shock as my bi for the month is R2325!!! Since I got my bill last week, I have been getting reference numbers. On Friday, 25 June 2021, they told me nothing has been done yet. I have called again today, it still has not been solved, again escalated. The debit order is due in two days, and they cannot stop it. The bank cant reverse it as it is an authorized debit order. I have changed to cash method, but the debit is still going off