Error trying to buy something from the PS Store

[DIRTY-SHAWNCHEZ_PSN]

My sister bought my nephew a Digital version PS5 for Christmas and I said I would get him some games.

I went in and made his PSN ID and added my credit card so I can purchase the items and will take the card off afterwards.

Anyway, I'm trying to buy him this game, a free 2 week PS+ membership (he's getting a year on his birthday the 7th of Jan) and a stub bundle.

Well, when I go to checkout; it gives me an E-8210604A error.

When I research the error code; it informs me that I have to re-enter the CC info (done three times), use another card, or wait and try later.

I don't want to use another card as I get cash back on the one I want to use. I've deleted and re-entered the CC info three times, and I've tried multiple times throughout nthe day.

Naturally, the PS Support Bot is useless.

Has anyone seen this error before and off so; how do you rectify it?