False advertising and false information

On the 24th of November i bought an Mtn home wifi of month to month for R249.00 a lady by the name of Ayanda Ndlovu assisted me she told me i will receive a 250rand takealot voucher and also told me i need to make payment of R 323.7 of pro rata and the remaining is upfront payment for December and she told me i will pay from the 4th of January now yesterday i received an increase from mtn stating i need to make payment of R 307.00 I don’t know what amount is for and also they are busy trying to do a debit order of that amount in my account, please assist me they are a **** and they lie to people