How to change default payment method for NOW Internet, and other annoying problems?

I'm on NOW internet (until the ways to cancel it are fixed), and need to change my default payment method to the credit card that I just added. So I go into "Payments", and select "All payment methods". This brings up a window with my two payment methods, the one that I added to become the default method, and the one that is the current default (non-working). Each can be edited, so I go to try to remove the current default, so that the new card will become the default. I'm told that I can't remove the default one, that I need to add a new payment method, which I've already done, so that's broken.  The next step is that I'm offered the chance to configure the payment methods. That bring up another screen with both payment methods, both have a checkbox. There I check the one that I need to make the new default, and select "Setup". This is supposed to allow me to designate the card I added as the new default, but all I ever see there is "Something unexpected happened", and I have to leave that screen. Or if it isn't "Something unexpected happened", it's "Sorry this isn't working right now". Anyways, I've gone around that loop way too many times, nothing works. I was thoroughly amazed when I was actually able to add a second payment method, that took several tries, although I can't do squat with it.

So how are you supposed to be able to change your default payment method for NOW Internet, if both possible ways are broken? You can't get phone-in support for NOW Internet, that's not allowed since it's a lowly prepaid service. So no support when the admin tools just don't work, that's really counter-productive.

Is this going to be fixed? I tried the Xfinity Assistant chat, and it freely admits that it doesn't have payment configuration functionality at all. As far as I can see the "self-administration" tools for NOW Internet are really broken. Key information and settings boxes contain a dropped ice cream cone image instead of whatever they should have, since the information and settings that should be there are apparently unavailable. What alternatives are there to get anything done? I'm about ready to just give it up.

Tried to upgrade to "Connect More" from NOW to get out of the NOW swamp, but couldn't cancel my NOW Internet using any of the methods that are supposed to work, so that turned into a big mess, and I've had to come back to NOW. Leaving Xfinity is my next move if I can't change the default payment method, since NOW will cancel my service anyways if it can't get it's monthly autopay. Come to think of it, maybe that would be for the best.

Pretty disgusted with the whole NOW Internet thing. The internet service itself works fine, but that's about all that does. At least for me, hopefully others are having better luck with this ball of [Edited: "Language"].