Working fine for me all day in Dublin city centre. Where are you located? What doesn't work? Nothing at all or just some services? What happens if you do a manual search for networks and try to connect to 48? Are you sure that you have a valid active membership with non zero allowance balances?
Hope this helps.
I am not a 48 employee so if you need to contact 48 support then use option 3 or the chat facility here.