Contract

I have a sim only contract with MTN and the 1st 2 months they loaded the data deal i had subscribed for which was 20G all day and 20G night surfer and i am paying R199 on the deal. Since the lockdown i found that they only have been loading 200 MB. I have tried calling the call centre no luck and i have written to then still waiting for the issue to be resolved. This month again the debit will go off but i have not been getting what i signed up for. I want to cancel the contract and look else where.