Hi Olly,
from the photos posted looks like APM is the "bodyshop" you're mentioning. Looking at their website here: http://apmcustoms.co.uk doesn't look like they are a bodyshop / specialist place, but a car wrapping place?
A bodyshop shouldn't have trouble making replica body kits / parts like the ones in the photos fit perfectly. Did the seller say they are straight fit out of the box or some work / preparation is required? If they did say it will be a straight fit, then speak to the seller and ask for replacement or refund.
I had someone else come out who runs a body shop to see whether he would take on the job, not apm, that's just where my car is getting wrapped and the parts were getting fitted (the simple ones). The person from the body shop didn't want to touch it, he said it has been an old mould so the part over years has just gotten smaller and smaller. I am just posting in here asking for opinions before anything else proceeds, I understand that fettling is always going to be required, but wondering where the line is.