While it could easily replace your wallet, its numerous other functions make this pocket-friendly tool even more valuable.

And an email on 7 October said: "We’ve been notified by another supplier that you'll be switching to them… Will they really save you money? "We're generally the cheapest or near enough ...

The Money blog is produced by consumer and money live reporter Jess Sharp and editor Jimmy Rice, with additional reporting from the Sky News live team. 07:02:19 ...