Yes, I did it and they solved it; the annoying thing is that they required a proof of purchase to proceed.
They surely have some sort of stamenent from google (I payed through Stadia) that tells them I payed for the service; it's surely strongly authenitcated and non revokable, why would they need to review my invoice, which also contains data I may not have wanted to share?
Thanks anyway, your suggestion may help someone else in similar situations.
We appreciate the update that support was able to assist with this ESO Plus issue. With the issue now resolved, we will close this thread from further posting.