2.0 cdti Insignia, loss of power and boost leak code, not the intercooler pipe, any ideas ?

[Eastbank st.]

Hi all.

I have a facelift Insignia 2014 + 2.0 cdti eco flex and a few weeks ago I had the garage replace the timing belt on it, right after I thought the car was feeling a bit slower than usual, particularly when driving up hill. 

this gradually seems to have got worse and a few days ago when accelerating the car suddenly lost power as though the speed limiter was on, once turn engine back off and on its ok again but not until I accelerate, and then it does it again. it seems to be gettting worse and happens now hen i'm not accelerating as hard. 

 

I took it back to garage who did timing belt, no codes for cambelt issues but he said there was one for a boost leak.   I remembered afterwards that the big intercooler pipe had a split in it a few months earlier and I replaced that, so I am not sure if the boost leak code was from that time or if it is relevant now.

 

 

does anyone have any ideas what the issue could be, or what other common pipes or whatever jmight be causing this \?

 

thanks