1.6tdci new turbo no boost

Hi i am aware of the problematic 1.6tdci and its history i have been searching through the forums but still could not find the answer i am looking for. I have installed a new turbo and followed the bulletin that was issued. The 1st turbo was working fine until i lost boost. Been to 2/3 garages and they had mixed views on what was wrong with it some say turbo gone and other saying boost leak. Egr is blanked, dpf gutted. New turbo installed, sump, oil strainer, turbo feed pipe, gauze filter, banjo bolts all cleaned throughly, Car fully serviced but the problem is still there. Ive done a battery reset and checked the error code which comes up as p0299 and only shows up some times and is deletable and wont come back for another day or two. Is there anything else i can do to check for the problem i have only done 100 miles on the new turbo. That would mean the old turbo should have been fine. I have checked both sides of the shaft on both and there is no play they both spin freely. Is there something im missing. Your help would be very much appreciated. Thanks.