Breach of contract

I have a serious problem.

I upgraded my contract on the 02/12/2018. I have a signed contract for 24Mth MTN Made For Me L (40GB DATA).

you will see that I only have a 24Mth MTN Made For Me L contract. Now the only reason I continued with MTN, was because MTN was giving me 40Gb data on top of my Made For Me L.

I have a signed copy of the contract. I am absolutely appalled at this outrage. How is it possible for you to get me to sign a contract and then go and deliver to me something different with a different charge. The debit order I signed to be accepted is totally different than what I is being debited.

Isn't that *****ing?

I do believe that this is a breach of contract. I really would like no more dealing with MTN after this. This is absolutely unacceptable.