Unnecessary Payment rejected fee's

My banking details changed at the end of last year, and since then, I have paid my account via the Telkom portal as I couldn't do it via EFT. I have never had an email or a call to say that paying via the Telkom portal is unacceptable. I got my latest invoice on the 5th of July and I was charged over R400 for a payment rejection fee - I asked them to cancel my debit order as I will be making payments on their portal and they refused to cancel my debit order which means that I will be getting charged another R202 extra every month for a payment rejection fee!!!!! I called Telkom today and they refuse to credit this. They also refuse to cancel debit order. I prefer to pay by via the Telkom Portal and I can not see that this is a problem. I just feel its really unfair as I pay every month... I refuse to pay this extra amount every month!!!