If you receive a call from someone purporting to be calling about Fraud then always end the call and phone your bank using the number provided which is  either on the back of your debit/credit card or on your statement. Often you get a text message asking you to call a certain number. I received one from my bank recently regarding suspected fraud on my credit card. When I called the number I was asked for personal information I declined to give that over the phone and immediately called the HSBC fraud line. In my case it was a genuine message and they were checking a payment I wanted to make, however it pays to be careful.