VODACOM is ridiculous!

Vodacom is the WORST!!!! I have cancelled all my contracts with Vodacom but they still manage to ***** me over! I had a cell contract with them for 20 years and a data contract for 4 years. I cancelled the last mentioned end of Jan, the last debit order I reversed and paid for by EFT the same day. Now I am billed an additional amount of R100.88 because I cancelled the debit order. They DID however receive the payment. HOW IS THIS EVEN LEGAL???? Now they want to hand me over to the legal department for the R100.88. What a JOKE!!! Vodacom do you feel good *****ing from people like this???