turbo unit is dying! has it happened to you?

Hi folks, just a wee bit of advice...

have a lovely octy vrs 2,0 petrol, feb 2006, nearly 90000 miles. it's served me very well up til now.

upon getting an mot check and full service, and investigating a low, and irregular idling speed at the local dealers, they uncovered that the turbo unit is on its last legs and probably needs replaced sooner rather than later; and this in turn has been probably affecting the idle speed and has knocked the economy to the wrong side of 30mpg, when previously one would have got 33-34ish without too much bother.

just wondering have many folk found themselves in the same boat? and if so, is it a dealer job, or is it a competant local mechanic job? the timing belt/water pump replacement job is overdue as well. does the turbo need to be exactly the same VAG part, would another create difficulty with the engine management? not looking at this as an opportunity to soup the motor up, rather to keep it going healthy for as long as we can as we can't afford to replace it! when i bought it both myself and the wife were working full time, there was no recession, no childcare costs and a smaller house, and all of the above have changed since then!

let me know your experiences!

thanks, alan