Just guessing - it makes more sense if you read 'hoses' instead of 'hole's' (maybe he has Apple autocorrect

)
hi, my 2000 catera, has been in the shop for the last two week, the auto shop guy can not seem to work out how to attach the two hole's hoses without them popping off due to oil pressure. the old oil cooler was take out and the after marked market cooler was attacted attached to the radiator, to which the two holes hoses run to where the oil cooler was removed. this is the area that the holes keep popping off. anyone have any idea???
Firstly - I can't see the point of changing the factory fit oil cooler, but that's another discussion....
Second - The original oil cooler doesn't have(need?) a thermostat because the cooler is sat in water at a temperature controlled by the main thermostat. An aftermarket air cooled oil cooler will need a thermostat. This thermostat needs to bypass the oil cooler when the oil is cold otherwise no oil will get to the bearings and the engine will be trashed in seconds. (It will also generate a high pressure in the oil hoses)
Thirdly - I have no confidence in your auto shop guy. He either doesn't know what he is doing or has made a basic mistake in the pipe connections to the oil cooler thermostat.
Fourth - The oil will be hot and at high pressure. Rubber hose and hose clips isn't going to cut it. He should be using Aeroquip (or similar) steel braided hoses with swaged couplings.
Good Luck. I think you need it.