Poor customer service

On January the 4th I've submitted notice of termination of my contract which was about to expire. And few days later I decided to send another follow-up up email and I only got a response after 1 more attempt. A consultant called me and we verified my details and processed my request. She then asked me if I'd like to keep my account in case I might need to take an upgrade offer at any time.i made it very clear that I don't mind to keep it as long as I won't be billed .she advised me to send a migration request 1 day after my contract lapses and that's what I did. On February the 6th I contacted her and she processed my request .On the 7th of February my last debit order went through and I thought I was done. 1 week later I receive monthly bill( due 3rd of March 2022) for the same contract I indicated that I'm discontinuing with and added migration fee which I wasn't even told about. I immediately reached out to mtn on Twitter via direct message and all they did was to escalate my issue to where God knows.i called customer care line I was transferred from one section to the other only to be told their system is offline they can't access my profile. I then decided to raise my concerns with the same consultant via email and 4days later still 0 response. I gave more than the required 20days notice and didn't use their data so I'm so irritated right now and I wanna close that line permanently.