Thank you for the unsolicited overly simplistic explanation of something I already understood. It's impressive how you entirely missed the point while writing that.
The cost of accepting payment via credit card has for decades now been baked into the price of the services they provide, and they have been incredibly profitable in doing so. Adding a new fee, at this point, is double dipping. Understandably the customers affected by this double dipping are upset.
A discount for customers using alternative payments would be the honest route to go IF the credit card processing fee costs more then other methods.
I personally suspect that it is actually more cost effective for Telus to accept credit card payments then it is to pay for the infrastructure to process cash and cheque payments.
Hence we arrive at people like OP, making payments via multiple cheques as an act of protest to increase the costs incurred by Telus for gouging their clients.