when i tried to play multiplayer, there was an error saying "the match making service is currently unavailable.

what give?

Nice name...

Which game? SCPT, SCCT, SCDA? If it's PT you're out of luck, as UBI took down the PT servers for "lack of interest" from the community - shame on you UBI!

If it's CT, either they are working on the servers or you have other networking issues that are blocking your access to them. DA shouldn't be having any problems ATM, AFAIK...