Try taking it back to them first to see if they could diagnose the noise ?
Only squeaking i could think of for exhaust squeaking are the exhaust mounts ? even then i dont think theyd make such a noice
ahh isee, thaat seems to be he case of supply and demand.
have you also tried gumtree ? the parts for older cars are starting to become more difficult to find.
need to change backing plate too as rotors will be larger. imo; if you are using the car for daily duties, the front of aurion brakes work very well too, cheaper than kluger brakes