Hello, my name is Mark and I will try help you with this.
I think when the garage told you the engine had been run without oil they really meant it had been run with low oil pressure.
The amount of damage done to the engine is not easy to determine.
What you need to do is decide how much money you are willing to gamble on having a few checks done.
There is a chance all it needs is new crank bearings and big end bearings but the crankshaft itself is not damaged.
The only way to determine that is to remove the sump pan and then visually inspect the bearings and crank.
If the only damage is to the bearings then these can be replaced along with the oil pump.
If the crank is damaged then you will need to remove the engine and gearbox, remove the crank and have it either replaced or reground.
This is where the gamble is. If you pay to strip it down and it needs a new crank, main and big end bearings along with a new oil pump, gaskets labour etc, and you decide it isn't worth repairing then the money spent is basically lost.
If you just decide to replace the engine without investigation then you never know if it would have been worth doing so.
Do you still need help with this?
Thanks for your response, I've just gone and got a reconditioned engine, just a bit dissapointed it failed after 45000 miles.