Hello how can I pay for my plan I changed credit cards , the system won't let me pay?

So I changed credit cards so my old one didn't work so I changed my default payment to my new card. After that the payment didn't go through even though my credit card has more than enough left in the balance. I tried adding my new number again and it tells me there's too many credit cards added even though I deleted my other two previous payment options. Any way I try to do it the site is blocking me what do I do I need service now