Just to close off the thread...Garage phoned said oil pump and balance shaft replaced but engine has a loud rattle which gets louder the longer engine is on or accelerator is pressed, he says I will be lucky to make it 200 miles to Scotland and to investigate and fix it the cost will end up more than the car is worth so he suggested he will wipe my bill and make his money back scrapping the car. Said since its took 4 months he wants to do me a favour.
I still think he is being so nice is because his garage done the damage but unfortunately no way to prove it so it looks like a sad ending for my reliable 2008 a4 saloon.
Cheers for all the information previously guys.