I've done that, but they may take seven days to reply, and I am not
sure if they can access my specific card details or fix anything.
When they respond I'll see.

They may take seven days to reply but they have been a lot quicker when I've
used them. They are just another arm of the Oyster Helpdesk so they can
access all your details and fix things and process refunds. Quite a few
people have expressed the opinion they are more knowledgeable and efficient
than those manning the phones.