Audi A5 2.0 TDI Turbo

[John M]

Hi Everyone, just had my Audi diagnosed as having a Turbo issue and garage saying to me that it's going to cost £2700 to have it replaced. I'm a bit concerned that they haven't checked everything as the car has only done 60k miles. Have changed Glowplugs and Pressure glowplug and filter however there is Black smoke coming out the back end when I accelerate. 

Any of you Audi Boffins have any ideas or do you know what the best thing to do is to get the cost down? Thanks in advance for any advise.