Unreasonable Charge - Debit Order Rejection Fee

An error with my bank resulted in Telkom's debit order being returned unpaid. After making payment to Telkom , I am informed by the consultant that I would be liable for a debit order rejection fee of R202.72 (increased from R100.52) basically meaning I pay R303.72 all inclusive. I made it clear to the consultant that this figure was something I had never been made aware of and that I wanted her manager to contact me. As is always the case, the manager was in another call.It was expressed to the consultant that I did not agree with the fee, nor the ridiculous +/-100% increase (from R100.52 to R202.72) and that I would not pay until a manager explained it to me. This according to me is ********* and bordering on **********. How can Telkom charge a fee for payment rejection and your bank also does the same. That's is ******* After speaking to a consultant this morning, I was told that Telkom increased the rejection fee because they found they weren't making enough of a profit...which begs the question how you came up with the fee in the first place. How is it possible that this can happen you get a payment rejection your own bank charges you and now Telkom has initiated another charger that is not available in the contract.