Contract phone on arrears

Hello Peter I took a contract phone at Vodacom last month I was told dat they will debit da money between 4-5 on may I shud keep ma money on ma account so they didn't take a money on dat two days they went to ma account on the 7th which it wasnt da date we agreed on wen I went to pay they said am owing 358 I was already in arrears for their own mistake today I went there again to pay da 100 penalty fee when I check I was already owing R506 I asked them how come they said I shud phone their accounts office which I've been doin wen I call them they send me to da shop so now I want them to fix their mistake so I can continue pay for da phone Nd one of their worker told me dat they can't do a sim swap for cuz am in arrears plz help me I've been goin in Nd out at Vodacom without any help