Vodacom worst service provider ever!

i paid my account via eft and then called vodacom to cancel the debit order and they told me there is no debit order on my account and then a few days later they tried to debit my account twice and i called them and they said sorry they see my account was paid but i will pay a R100 penalty fee for each time they tried to debit my account. im sorry i will not pay any penalty fees because of your useless staff's fault !!!!