No more auto pay discount? No Customer Service contact?

ahuber86 wrote:

I recently tried to update my auto-pay, and was unable to. Apparently, T-Mobile no longer takes credit cards and won't take my new card, and is saying they're taking away the auto-pay discount unless you use a debit card.

It appears it has been established that T-Mobile has removed the discount on using credit cards on autopay.

But, has T-Mobile also removed the ability to use a credit card on autopay?

I currently have a credit card on autopay, but what will happen when I need to update the credit card, either through change in credit card, or updating the expiration date?