Since when is your connection not working anymore?
AT+CSQ always returns 99,99, AT+CGATT? returns 0 so there is no connection. Two boards here were working just fine until 10:30 or so yesterday, then I noticed them retrying and the AT+CSQ 99,99.
On Monday I saw an error on the maker.allthingstalk.com console with the word 'exceeded' in it, but I am not sure at all about that, I was busy with other things and planning to get back to that message the next day.
Maybe someone else has noticed error messages, if so, could you please post them?