Why are we being penailzed for paying with a credit card?

Let's be real, were it the extra 1% to 4% T-mobile is charged they could simply net down the discount by a fixed amount.  We all know that they are paying closer to 1% of the discount back for processing, but math helps: $5.00 per account is 5 to 20 cents, maximum.  So credit card payers get a $4.90 or $4.80 discount, check and debit $5.00 and few people leave. 

Again, reality, my discount is $30. So I'm tempted to find an expiring debit card that must be updated monthly.  Or a single use bank account that autopays simply to protect my real bank account from exposure with no back end protection. I'll bet those thefts reported here of credit card numbers by employees left Tmobile a considerable expense due to legitimate charge backs since they didn't adequately secure the data. Plus the possibilities that former customers leave without paying when frustrated by mistreatment, real or imagined. 

I pay my bills but might be better served by lower priced MVNOs and nearly $400 a year is incentive enough.

From a bigger picture these are the kind of moves companies that don't feel competitive pressure make, just as we were warned when Sprint was acquired.  It's time the FTC looked at existing ologopoly markets like telecom and airlines. Unbreaking eggs is possible but it takes hard work by lawyers as in Standard Oil and consistent enforcement, not like AT&Ts regional monopolies.

How about you not close this as answered T-Mobile? Answering it with a self-serving response from a deluded customer is malarkey.