Trying to upgrade, won't accept payment

I am trying to upgrade two phones on my plan. I went into the store and they told me if I did it online, I'd save money. I tried doing it on the app, didn't work. I tried on my laptop several times and when I get to the payment part, it says We Couldn't Process Your Payment.

I tried two different cards, one debit and one credit. Both have ample funds available. I cleared cookies and cache...no different.

I called and they wanted to charge me the activation fee. The rep said he would waive it, since it appeared to be the site. He went through the entire process only to get the SAME results. He told me to call my bank to see if I had enough money 🙄.

So I’m back to square one. Any advice?