help with loss of power black smoke

Hi,



i know this topic has been some before and would indicate its the EGR, but please bear with me.



initially there was a light on the dash the orange one but no fault with the driving of the car, so i took it to the garage i bought it from to reset / fix this, they cleaned the EGR & reset and was ok.



Next day the light back on they replaced the EGR with a new one.



now this is when the black smoke and loss of power started happening, but if its a new EGR?? or have they fiited a re-conditioned piece of crap?



also there is a slight turbo hiss noise, but im guessing they have disturbed a pipe while changing the EGR?



any advice before i take it back to them would be appreciated