Thanks, I Got support and they have fixed the issue. I have an android phone and they got me to do the following. Go into connections / mobile networks / access point names. This was listed as Tesco mobile internet.
They got me to delete this APN and add a new one with the following 2 settings. (1) Name - 48 internet (2) APN - 48 months.liffeytelecom.com
Once I saved this I made sure mobile data was turned on and turned wifi off. Mobile data came back on.