MTN stuck in lockdown?

We took out an unlimited data contract years ago. During lockdown we noticed that we were unable to use the contract. We contacted MTN telephonically, via email and in branch. We were told that the contract was an airtime contract and not data. For months now we are struggling to get MTN to respond. The latest we were told that the contract was erroneously migrated to airtime. We had to do a simswop to try and see what was going on. We are paying R350 per month for airtime we don't use, need or asked for. We have sent so many email without as much as recognition of email received or a ref nr. The service is absolutely pathetic and unexcusable.