cambelt changed by vw dealer and they notice engine knocking when warm

[northernmunkeh]

i'm at the end of my tether, it just keeps getting worse! 

latest - car went in for 40k service + cambelt + waterpump at a vw dealer

after the work is done they notice an engine knocking noise when its warm.

they then try to get £79 out of me to pay for the fault finding.. 

it is being investigated now but I just think this "approved used" gti is fubar and I'm better out of this before it gets any worse. This has occured just 5 days after getting the car back, it having spent 3 weeks with a vw dealer having a new air con compressor fitted as well as new aux belt that snapped when compressor seized, causing the car to actually breakdown 
 

[CaptainJack]

isn't this the one that broke down, mate? sounds like a lemon. i am really sorry for you.

[northernmunkeh]

aye it is mate, thats the one

: (

[PDT]

was there a knocking noise before the cambelt and waterpump was done? have you listened to this 'knock' yourself?