Pipe cutter on carbon steerer :(

I took my new frameset to my LBS to get bottom bracket and headset fitted.
I left the shop and when I returned minutes later I saw the mechanic using a pipe cutter to cut the carbon steerer! I stopped him and told him he should use a hacksaw and guide but the cut was almost completed. He said he will complete it with a hacksaw but he didn't understand that the damage was done (the creaking carbon should've been an indication).
I have no intention of riding a delaminated carbon fork and I'm not sure he'll admit causing any damage or agree to replace the fork!
What should I do if that is the case?
Thanks

Assemble your evidence and talk to the manger / owner of the shop about a new fork.

Out of interest which frameset / fork?

Next time do things yourself.

Name and shame the shop?
I guess try and sort it out amicably first, but that is ridiculous.

Shocking.

Even with a hacksaw you should be careful and use a higher TPI blade or even better a tungsten carbide one, I am going to guess he hasn't had much experience with carbon - either way that isn't your fault, it's the shop - they should be liable for it sorting it out and surely the fork is pretty good evidence he did things wrong!

Hope you get it sorted.

Epic WTF

All mechanics carrying out contracted works must do so with reasonable care and skill, he has not. I would endorse what @Howard says…

what shop?

Personally I wouldn't name and shame until all other avenues explored. Owner of shop could immediately accept responsibility and supply a replacement fork and training for staff, for example, and everyone is happy.

Or they could make a fucking meal of it in which case, yes, name and shame.