Hi Robjay
What belt did you change? timing belt or the normal belts?
For the oil could be wrong engine oil specs it maybe 15w/40 but the API Spec is below what is required, it may also be the wrong Specs totally like maybe using too thick of a oil like 15w/50.
As for the knocking sound of the brakes might be the mounting bolts that they remove to flip the calipers to access the pads are not tighten properly. Had this myself once after brake pad change and forgotten to tighten it tight but just tight.
As for the rest or more possiblities i rather not post here as it could be potential court case for me. I have never trusted all this "***PM ME FOR NAME***", or so call big companies due to a few things of my other cars that i have gotten quote for repairs and such that it will cost me 4 times more than my "back yard" (workshops found in industrial areas but not BIG franchiees types still Mita certified) mechanic charges.
Eg: My wife's 92 lancer had pick up problems took it to my mechanic told him the symptoms test drove with him and told me during the drive the distributor cap is fark and would cost me about $90 original champion (which mitsubishi uses) plug cable and the brush in the cap all changed but he could do it that day due work load. So i drop by my area's ultra tune quoted around $350 to $400, Auto masters $350 to $450 for trouble shooting, parts generic as they say original will cost too much for an old car and labour.
Chances are also that for $130 service package I really doubt the type of oil they use more likely than not its just ordinary minerial oil not suitable for turbo cars.
Personally if i were you driving a import car i rather do this minor servicing and trouble shooting and repair myself, and i'm sure all the bros in here would agree too as the moment they see its and import they bring out their sharpen swords to hack you. "OH IT COST SO MUCH IS BECAUSE ITS AN IMPORT SO THAT PARTS ARE VERY MUCH MORE EXPENSIVE" line
Look up KYP and look for Ben...he did my manaul conversion and i've no complains about his work and also willing to share info or quries that you 'll have
My 2 cents worth