Help! Car makes rattling noise when I change gear or accelerate and burns after long journeys!?

Ok, so on december 8th my little car had its m.o.t, I drive a ford fiesta encore 1998 1.3engine, the work needed cost me around 拢180 and so I got it done because I need my little baby. Lol. Now a few days after that I noticed some rattling I called the garage me and dad have being going to for years as the guy is a family friend and he said since he just fitted a new exhaust for it, the rattling noise I hear will just be the exhaust finding a place to settle and the burning was just the coating or something on the exhaust because it was new can't remember his exact words, this was when it only happened every now and then so I left it, now though iv noticed that its getting gradually worse, the rattling is louder now when I accelerate or change gear, and when on long journeys there is a burning smell too. I don't have time to take it to a garage as I work 7 while 6 everyday but sunday so can't get it in till next week need some kind of idea how much or what this is please. Bear in mind i'm only 20 so if its something complicated can you explain what it might be. Thanks in advance Xxx btw the rattling is under the passenger side. I couldn't work out where is was coming from in the beginning or I would've known it wasn't the exhaust lol.Help! Car makes rattling noise when I change gear or accelerate and burns after long journeys!?
It's likely that a ';Baffle';, within the silencer part of the exhaust has broken loose and is rattling within the box. Eventually the rattle will subside due to the baffle getting stuck in the 'soot' within the box. Secondly, the smell IS as a result of a new exhaust part being fitted and burning off any labels and grease from manufacturing. This may also be the reason the Silencer is now rattling, as the repair to the exhaust has caused the baffle to break loose, due to the tugging and pulling during the part refit.

Leave it for a week or two and the baffle will find it's ';new home'; within the silencer, and wedge there and cease rattling.Help! Car makes rattling noise when I change gear or accelerate and burns after long journeys!?
Without hearing it, it's difficult to diagnose but it's certainly possible it's the new exhaust. New exhausts do have grease, paint, labels etc. on them which will burn off as they get hot. It is possible that the silencer has a faulty baffle in it, but it's much more likely that the way it hangs just needs a little adjusting to stop it hitting the floor or something. A very simple job which doubtless he'll do for nowt since he fitted it in the first place.