Website Won't Let Me Make Payment

Hi, I have not had internet for a few weeks now, and the website will always end up in error when I try to change my card and pay. If I try to add a new card, the website just goes to "Error." If I try to resubscribe, make a payment,  "Error." I've tried any Xfinity support instructions, tried going incognito for the load time, so now I'm here.

Can you please fix this? Are you able to take my payment through customer service? 

Thank you.