Forcing to debit my account

Telkom has got this issue of imposing bank accounts on clients, I'm their client don't have a bank account, our account says I must pay them on the last day of the month I do that without a failure but every now and then they will sent u an invoice with a R200 of some failed debit order or something it's like a reconnection, like they went to your account to collect and didn't find anything now they are suspending your account unless you pay the R200, 1 consultant at Killerney Mall boldly said to me I'm lucky they don't charge me those R200's every month, I've pleaded with them to change my method of payment from debit order to cash payment because the work I do doesn't need an account as I do odd jobs, get paid by cash or cash send or ewallats but I never fail to pay my account. They say their debit orders run on a certain day so the day I pay my account the debit orders have already been sent to the bank but they don't return my payment and say noo your late, they take the payment and penalize me, this is unfair on me I need my method of payment changed on that account because I can't commit to a debit order as I don't have a active bank account.