Billing for Service provider's flaws.

Called vodacom this morning to complain about later deduction that VC is doing on my account and now I have to fit the bill for late payment. Agreement i have with them is for debit order to go through on the last date of every month. now VC failed to adhere to that arrangement, two days later D/O goes off with a extra charge of 200 where by my monthly installment is 511 ended up paying 712. This not fair for client to pay for Service provider fool systems.