"Keep your debit card in an RFID blocking wallet or sleeve"
Some blocking wallets and sleeves can be bypassed with a stronger signal. To get round this a new generation of blocker cards are available which use the energy from the scanner to generate a blocking signal. Early models used to set off store door security scanners. New ones are okay. Just slip the card into the wallet and you are covered.
New RFID Blocking cards include Blockr Ultimate, and Savisto. Prices are usually around £8 per card but at the moment you can get a twin pack of Savisto from Amazon for £5.95 with free delivery. Orders limited to one per customer but you can re-order. https://amzn.to/2RMpdO9