MTN taking off too much money again

I, Maureen Adams renewed my MTN contract end June 2021 and was advised by the consultant as well as confirmation from the company via sms that i had a 0 balance. My new contract is R369-00 and as explained would be the amount I pay for the duration of this contract. On 1 July, an amount was deducted from Standard bank account for R540.50 and 02 August 2021 the amount deducted was R490.97. I have called in to the company regarding this matter at least 3 times but received stories which did not confirm what i originally signed into. I feel that MTN is not upfront with delivering the service that they are meant to be for a company of that size. This is not the first time that i am experiencing an issue regarding this matter and am requesting that the correct amount of R369-00, which i signed for initially be deducted monthly and that there be no hidden extra charges. Also requesting a refund for the extra fees which i am being charged. This company makes so much money and as a pensioner, i am only able to put enough money into the account for my debit orders. Why do they do this? Mobile ***.