Mystery Caller is planning to go travelling in Europe over the summer. He already has a phone but needs a SIM-card that won’t cost a fortune when used abroad. What deals do the networks offer for roaming?

Mystery Shopper regularly travels across the UK to do business. He needs mobile broadband with enough data to make Skype conference calls, email and download presentations. What will each network offer?

Despite a sleek design and decent battery, this tablet fails to live up to its early promise due to a poor camera, below-average screen performance and underwhelming processor 

Mystery Caller has always used phones made by HTC and is looking to get himself a new device. He wants it on a monthly deal for under £30 – what phones will the sales staff offer him and who can come up with the best deal?

Mystery Caller has seen adverts for the new LG flagship, the LG G4, and decided he wants one. Which operator knows the most about the device and can come up with the best deal?

Mystery Shopper wants a smartphone designed for consuming media – movies, music, games etc. It’ll need a good screen and audio. What can our retailers come up with?

All of the retailers have said they are stocking the LG G4 handset, and Mystery Shopper wants one. Do they all have them in stock, and if not, what alternative will they offer?

The Surface 3 is an attempt to turn the Surface Pro line-up into a more manageable device

The fourth generation of LG’s high-end G series hit the sales floor late last month, but does the £499 price have the power to unsettle rivals Apple and Samsung?

Mystery Shopper wants to buy a tablet with a data connection as a present for a young relative. Can our retailers find him a good deal and explain what parental controls are available?

The Galaxy S5 from last year was underwhelming and played a part in the manufacturer’s global market share slipping. Can the Galaxy S6 edge help to turn around its fortunes?

With each new generation of handset comes a new flagship, this time the One M9 from HTC and the Samsung Galaxy S6 and S6 edge. Can the sales staff explain the differences between the new devices?

Mystery Shopper needs a device that can survive exposure to water after a few unfortunate incidents. Can the retailers explain what an IP rating is and find a device that can endure a quick swim?

It has a cool Edge with plenty of innovations including a camera relocated on to the spine and away from the clutter. Could this be a device the company’s boffins have thrown at the wall that will stick?

It is smaller than its predecessor but is a HTC device making it a ‘dream partnership’

Android and iOS devices both include a range of features for people with visual impairments. Mystery Caller wants to know what these are. Can the CSAs tell him?

Mystery Shopper got a brand-new a new LTE-enabled Nexus 9 tablet for Christmas but there was no SIM card. Can our retailers find a good SIM deal and explain network locking as well

The Samsung Galaxy Note 4 has been hailed as the phablet with the class-leading screen and display with the best implementation of a stylus. Our resident geeks on What Mobile put the claims to the test

Windows Phone is growing in market share so Mystery Caller wants to see what is available – but he won’t pay more than £20 per month. What can the CSAs offer?

It’s Black Friday and Mystery Shopper is looking to take advantage of the sales to buy a Christmas present for a loved one. What prepay phone can he get for under £100?

Apple has launched the 5.5-inch iPhone 6 Plus. Samsung now has the Galaxy Note 4 with a 5.7 inch screen. Phablets are all the rage. So Mystery Caller wants one. What can the CSAs offer?

This week Mystery Shopper visits Durham, the land of the Prince Bishops, to look for a princely phablet. So, what is the largest device our favourite retailers can offer and can they sell it for a reasonable price?

Sony released its new flagship Z3 and Z3 Compact last month and Mystery Shopper wants one. Can the sales staff find a deal or convince him to take an alternative device or brand instead?

BlackBerry hopes its latest device can help it to soar again, but will the Passport’s odd design ground this flight of fancy before it’s even taken off?