Telkom account paid up they still take a debit orders every month don't stop it

I bought a phone 2years it's been paid up and telkom is still taking money i spoke to how many people at telkom and went into the branch they are still taking the money. I sent emails as well but nobody is coming back you can't get hold of the proper people. Every second day it's a different amount not what I use to pay on my debit order for the phone about 10 times more. Can someone please help me i don't know what to do anymore.