Contract offered by retentions not honoured

My previous contract came to an end in June this year. I called retentions to cancel, they then offered me a very good black Friday data and voice sim 3y contract. For the first two or so months I have been receiving the promised allocations, but then suddenly since October I have been receiving only a fraction of what I should.

I have called the customer care many times, retentions many times and no one is actually helping me. I even requested to speak with a manager at retentions and they put the phone down on me.

My local MTN store has tried helping and called customer care as they can see and acknowledge the error, but MTN customer care / retentions cannot. On the MTN system it does not show the black Friday deal, just the standard package.

The one time i spoke to someone at retentions they said they aware of a glitch in the system where a few customers were affected and that my number must be put on a list to fix, however this has not happened and every time I call in each person tells me a different story. There are some really *********** staff at retentions and with attitude.

I have proof of my data / voice allocations on my previous MTN invoices and SMS notifications of the bundles previously loaded. There will also be a voice recording that proves my case when I was offered this black Friday special over the phone.

I find it disgusting that MTN cannot resolve this, even the MTN store that tried helping gave up as it was futile calling in.

Please help, this is a breach of contract and I have exhausted every means so far.