Have they gone into settings and put the correct ones in for your data card, I don't know the settings for your data card but you could google that, to change to a giffgaff data card (I know that isn't yours but this is an example) you have to
Connect to the SSID of your TP-Link .. this info (including the password) is on a sticker on the inside lid of the
battery cover.
Login to the control panel. It should be on
http://192.168.0.1
Once in, click on the Wizard tab.
Click the next button.
On the Dial Up settings section, you must enter some new details [the standard O2 onces come on the SIM, you need the GiffGaff settings]... do this by clicking the Create button and entering the info below.. the password is 'password' (without the quotes).
View attachment 30978
Once entered, click Save, and make sure you new profile is selected in the drop down.
Now click Next to get to wireless settings... change these if you wish... I made the password a bit easier to remember.
NB, if you do change the wireless settings, you will have to reconnect to the
mifi once you have finished.
Click Next again to get to the Finish screen.
Click Finish to save the settings.
If you find your data settings and use them following the instructions above it should work