xbox live gold

I bought a subscription for xbox live gold but it doesnt work, I can use apps like youtube or netflix or play single player, but for example, I enter Battlefield 3 and I cannot play multiplayer, and my connection is faithful, and there is connection between
my console and xbox live. I tried to communicate with microsoft but it is impossible, I don't know what to do, I spent too much money between console, subscription and the game, to not be able to play.

:)