ehh, looks like you should be able to just pop the cover off, remove the screws and have a look-see inside; seems to be just a male coax connection...
is the cable not working? why does your client want to replace it?
if he/she's already got cable, the cable guy should have replaced it for them...
if it's in a building wired for cable, check with the maintenance guy, he
should also be able to swap in a new connector.
OTOH, it might just be a fiber-optic connector, not a cable connection; the wire looks awfully small for coax, coming out of the righthand side of the box, there...hmmm. is your client a new tenant or is this in a house? you dint say.
need more info!
thing about a switch-plate is...ya gotta have an in-the-wall or through-the-wall coax; switchplates are used to cover electrical outlets and cable/audio feeds, this on looks rather like an internet, not cable, connection installed by ATT (I have one that's similar, I think). I'd check on that first.
g'luck.