Driving over bumps or on a rough road rattleing sounds from outside almost like a chain rattle

Most door panels have push lock retainers you just have to pull the panel off by prying around the edge. they make a special tool for this but you can use a flat screwdriver just pry close to the plastic pins under the panel

I would start with checking the muffler and pipes to see if they move when u push on them. Make sure car has set for a while so u don't get burned

Check cv joints. check wheel bearings.. Check wheel nuts are tight and are tightening up on the center part of the wheel

Check sway bar bushings/links and sway bar bushing/body mounts, rattle mostly when going over bumps/rough spots in the road.

Why not check if its your exhaust rattling give it a shake and see
Or can be a loose heat cover

i used to drive a mk2 golf but now drive a mk1 and i had the same problem, especially when am turning. with my case when i had the rattling problem the cv joint boots needed to be replaced as they were worn out. that is one possible answer to your question. if youre DIY guy you might wanna check that out or go to your mechanic and he might tell you the same thing.

sounds like worn out shocks or struts

Check the tie rod ends and the upper and lower ball joints. possibly the hub bearings or the strut but I doubt it.

I dont know what kind of "tests" they could have done....But find a front end shop and tell them what happened and have them find the source of the rattle. Check the sway bar links, check for anything bent. Is the steering wheel straight? does the van now drift to one side or the other when the steering wheel is released while driviving? You coul dhave a bent strut. if so replace the pair and have a alignment done. Go to a independent repair shop not any type of Chain Store (midas, meinke, goodyear, firestones, tires r us ect.)

It's probably the rear sway bar links. If you can jack your car up and check right behind both rear wheels you will be abale to see the sway bar which is connected to short links about 5in long with ball joints.

If either of them are broken or not connected anymore it can cause some pretty loud noises when you ride on rough roads or hit bumps. They run about $35 per link so it's not a very expensive repair.