Telkom Irregular Charges

I'm on the Telkom Home Unlimited Contract 10mps. This contract is R807 / month

I have a statement that show i owe R1060.42 for last month. Made up (according to accounts dept) of R807 for the contract, R26.08 for a mobile contract, R202.70 for a payment rejection fee and R25.63 interest.

On the 31st October 2018 Telkom Debited my account for R900 twice (this is clearly reflected on my bank statement). I contacted Telkom who told me that there had been some errors on their side. I instructed my bank to reverse the 1 incorrect debit of R900. It seems as if Telkom then reversed the other incorrect error from their side.

My frustrations below (which the accounts department could not assist with):

1) How can i be charged a payment rejection fee for Telkoms Error? Had they not double debited my bank account, there would be no problem 2) I've been charged R25.63 for a mobile account which i have no clue off. The agent told me its for number ********** . I wonder how long they've been charging me for this? When i queried this with Telkom billing.. i was told that i have to contact Telkom Mobile. When it comes to taking my money, billing takes the full amount. But for queries....? 3) How can i be charged interest for Telkoms error? 4) Why did the deduct R900 from my Bank. R900 is the maximum they can deduct as per the limit i set. Surely my usage was less

The harsh reality is that i'd have to pay Telkom otherwise will cut my services