Inserted SIM card into new phone when got upgrade in March. A week later displayed no SIM message which was overcome by restarting the phone. Two days ago it displayed said message again and have not been able to resolve it using any of the suggested methods online. Went into O2 store and was told they the SIM itself seems to not be working and will require a replacement. How does one go about this, can I do so in-store and what are the associated costs given the SIM has been improperly functioning since it was inserted pretty much so I am unsure how it could be damaged. Thanks
It's free to get a replacement sim and any O2 store can do it for you.
Why did they not do it whilst you were there?
You will need to take ID with you though, so maybe that's why?