I had a similar situation where some dormant account was still charging my credit card.

The account was probably real, made for some purpose 15 years ago. I had ignored the charge for years because it was like $7 a month. Then it went to $300/month, making it worth the time. I could find no invoice email and none of my AWS accounts lined up with the bill.

I tried contacting support, but without the account number involved they had no way to help. I disputed the charge, the bank refunded that month and then went right back to charging the next month(my credit card helpfully accepted the charges despite the dispute).

I had to cancel the credit card entirely to make it stop.