BAD BAD SERVICE

In January 2020 I did an upgrade on my cell. I did not take a new device and the contract I signed was for 100 minutes airtime, when I queried if they did not have anything with 200 minutes I was told that I could take a 100 minute booster on the contract that would give me the 200 minutes I wanted. Since then I have only been receiving 100 minutes, when I queried it I was told that the booster was not available on the contract I had taken. When I first went to the store where I did the upgrade they showed me on the system that the booster was on the contract. After MTN told me that the problem was resolved and I still did not receive the Booster 100 minutes I went back to the store and when we looked on the system the booster package had been removed although I have a signed copy of the contract. According to me this is ***** because I have not received any correspondence about this change to the contract. What makes it worse is that they are still charging me for the complete package that I signed for. It is no good speaking to the people at the call center because they don't have a clue what they are doing and just want to escalate the problem. there is never a supervisor or Manager available to speak to. I am going to lay a charge of ***** against MTN for changing a signed contract after it was accepted by their system