TMobile can't find my bank Bill Pay Payment...I paid it!

I made a payment using my bank’s bill pay option.  I transposed ONE number when I entered the account, and now Tmobile is going to send me to collections for non payment.  My bank statement shows that the payment WAS made to Tmobile but the “back end” team in not able to find it.  It’s been FIVE months of going back and forth with Customer care.  I’m surprised and disgusted that a company as big as Tmobile can’t resolve this.  I’m a 20+ year customer.  I can not have our phones disconnected as our livelihood in business depends on working phones!  So it looks like I have to pay the bill AGAIN because of their incompetence.  What a scam!!!

I am going to cancel Tmobile and will take every opportunity to tell everyone I know how awful and apparently incapable they are.  Does anyone have recommendations on a new cell phone provider?