Welcome.
If you search the
Verified Database for "natwest" you'll see a few numbers that you could try. There is even one mentioned for Credit cards. If that no longer works or is not the correct department then I would generally act "dumb" and apologise for calling them and could they please transfer you. If needed then say you are calling from your mobile and therefore can't take down the number.
As always when ringing geographical alternatives, we recommend that the number is withheld.
In your circumstances, I'd recommend you try yourself and if successful then pass the number to your daughter.
Good luck