rattle after gear box reseal

[pockets]

hi , i have a rattle coming from my passat 2007 2i estate. i left car in for service was told my gear box was leaking told it needed resealed .got car back rattling sound when i accelerate . i took car back to garage and was told its your flywheel you need to replace it . there was no rattle before gearbox was removed and sealed and i would appreciate it a lot if anyone could help me out by answering if the guy at garage could have caused the rattle when removing gearbox and replacing it , has he not replaced everything correctly or was he near the flywheel? total novice when it comes to cars love my passat just wish id picked a different garage , thanks for reading advice appreciated .