Worst experience

I signed up for a data contract of 40G for 229 but the consultant made a mistake and give me 10G for R250 I have up and down the MTN store in Eastgate but nothing, I keep on calling the customer care but nothing I am being told that the contract will be sorted but nothing. It's been over 4 months and no resolution yet,i am tired of calling the branch and customer care because nothing seems to come out of it. Why is this happening? Maybe I am being too patient and understanding.