fault code P2263 garage make a mess of my car

hi all first post so if I'm in the wrong part then please don't shout.  please read all and advice would be greatly appreciated. 

My 2009 2.0 Tdci Galaxy had a coolant leak. Local garage had the car and they diagnosed EGR Cooler needing replacing. I was told car was now fine but once home the coolant carried on leaking. went back to garage who now decide the Cylinder head is cracked. ok big job £475+Vat part and 13 hours labour plus cam belt and water pump. its  very expensive but told them to crack on as needed the car.

got the car back and they've cracked my windscreen, they've said it will be replaced in the new year by their insurance.   i have  noticed a blow on the exhaust I would guess manifold area. 

I also now have a SASM fault/steering Angle sensor fault and a P2263 Turbo boost pressure fault/exhaust gases out of expected range. 

I've done a bit of online research and it's possible the actuator for the turbo isn't working correctly, if at all, and I'm hoping tomorrow I can get a good enough look at it without dismantling the car. garage is shut till Thursday but they assured me the car is still safe to drive after I explained the issues over the phone. 

advice would be great on if i should be paying for all these extra jobs that didn't exist before the garage changed the head as I don't see why I should be paying for something that they've caused. 

also if anyone has any other ideas on what the cause of the P2263 fault could be that would be brilliant. I'm guessing something wasn't connected properly or possible link to manifold gases leak. 

will also add that the garage is normally brilliant and very helpful. they told me about the windscreen crack even though it was right at the bottom of the window below the wipers and I wouldn't of spotted it. 

thanks all 

Paul