All of these services can give you a push notification every time a transaction is made on your account so that you are immediately made aware and are able to cancel them. You can block the card from within the app immediately.
1. http://join.monzo.com/r/vrlkxvo (Using this link gives us both £5)
2. https://www.tandem.co.uk/credit-card/
3. https://www.imaginecurve.com/ (Sign up with WAI91 and we both get £5)