Yes that's the pass. side. You might get away with the main tensioner ($70?) and a little time. The changing procedure is listed above by somebody else. Easy fix I should say.
Unfortunately, you are not the only one that has been fulled by not knowledgeable mechanics. This is nothing comparing with other things that I saw or read on this forum. Punching him in the face might not bring you any positive other than short satisfaction. Heads up and move forward. Just think that could be even worse.
JOY = BMW