A/C not working

Our 3008 was recharged 12 months ago. Has been regularly serviced by a reliable independent garage.
Has been out four times in the last two weeks due to UK Corona-virus lock down.
Today the A/C didn't work. Light comes on the dash, pipes are slightly cool to the touch. A/C was cold when used last time. No click when turned on and no A/C fan running. Have checked 40amp A/C fan fuse. The black cap that covers the refill (cylinder on the left front of engine bay) had snapped off leaving a small, loose piece of the plastic thread. Help!