Card blocked sticky referral what does this mean?

a sticky referral block on your debit card means that there has been some unusual activity that has been flagged by the fraud department, and they need to talk you through your transactions to make sure they're all genuine. its very common and usually turns out to be nothing to worry about, it can happen for example, if you live in london but your card gets used in manchester, and so because the card is usually only used in london, even making a small purchase in manchester would flag up on fraud detection systems.