Gat vat

Telkom mobile has the worse service ever, they decided to debit my account before my normal salary date now they wanna charging me R270 for a so-called return debit fee. When I took the contract (telephonically) no one told me about a return debit fee and the day they tried to debit was not my salary date and even if my salary date is on a weekend my debit is supposed to go thru the following working day, not the working day before my salary date. Jan 2020 they didn't debit my account, why? Who must pay for them not debiting my account? What must happen? I refuse to pay that fee because I didn't know about it and the day they debited was not as per our agreement