Got this call "Natwest Group Fraud Dept" with call back numbers 08453560020 and also +441313397609.
Called NatWest using details on Credit Card statement instead. They checked my credit card transactions, nothing flagged up. So left details of telephone numbers with NatWest.
Here are the REAL numbers with associated text from the Natwest Website (PLEASE check it out for yourself - to make sure I am not lying to you!)
"If you suspect that you've been the victim of fraud or notice any suspicious transactions on your NatWest account, you can report this to us by telephoning 0845 300 3983 (24 hours a day) or by contacting one of our branches. From outside the United Kingdom, please telephone (0044) 131 523 8383 (24 hours a day). Please note that charges can be reversed on calls from abroad.
If you need to report fraud in relation to a NatWest credit card, you should telephone 0845 300 4350 (24 hours a day). From outside the United Kingdom telephone (0044) 1268 508 020 (24 hours a day). Please note that charges can be reversed on calls from abroad."