Yes Peter. If I remember correctly, I can connect but there's no Internet.
Could the sim card have expired or could the allowance be finished? Once you are connected to the MiFi's wifi and you know that the MiFi has a network connection then try entering https://www.three.co.uk/My3Account2018/My3Login into your browser, Jean. You may only need the first bit but if you are copying and pasting the link then try the full thing.
If that doesn't work then it would seem possible that you haven't connected to the MiFi's DHCP server and so aren't properly connected. You could try a software reset of the network adapter on whatever device you are using.