DATA Shortage but full amount Billed

I entered into a DATA contract with Telkom on 30 November 2020. According to the contract I was supposed to get 40GB anytime and 40GB night surfer, wich is a total of 80GB per month. I only got 75.96GB instead of 80GB. I logged 2 calls to report this issue. The referance numbers are ***6 and ***8. Both cases were closed without resolving the problem but I was billed the full amount. Telkom I want the DATA you ****** me or pay me back my money equivalent to the DATA shortage.