[Cliffradical]

Oh boy.

There's some kind of airseal issue here, or several. It's unlikely that the tech ruined anything, there just hasn't been any effort put into "making things work more better".

If it was a simple (especially complimentary) spring swap, it's nearly guaranteed that zero effort was put into anything other than a straight spring swap. That's understandable, but the service stuff your tech did wrong regardless which sticks out here is

A) Giving any kind of explicit or implied guarantee on fps targets without selling you specific 'tuning/ compression' service
B) Giving an estimated completion time less then '7 business days' or "when it's done"
C) Not doing a chrono/ function check on sign in

I've been on both sides of the counter for situations like this. From the customer perspective, you are paying good money to not have to worry about something, so having to worry about it after paying money is pretty much the worst. From the tech perspective, you can sometimes do everything right and still fail, but if you don't set yourself up for recovery through ass-covering policies and huge windows of work time to sort out problems, you end up looking like (and feeling like) a wiener and that's pretty much the worst.

If you paid for tuning/ compression service along with your spring swap, they should definitely be getting this gun to match their claims.

If you didn't, well, it may be a case of rushed/ half assed work or it may be bad parts and QC in the gun (you got a lemon, it happens) which they have no control over. They may have led you into false expectations, however, which they need to own.

If they seem to be trying to make good on it, take them up on it, if you didn't pay for 'tuning' service or whatever, maybe offer to meet them half way on costs or something.

No doubt the tech/ business wants to retain a good reputation and customer, but then you're unhappy with the service you paid for. Don't be a pushover, but you'll get more bees with honey than vinegar if these guys are decent folk. The tech guy is getting it from both sides right now, so if you're at least kind of nice to that guy he'll probably be inclined to go farther with it rather than being stressed out and wanting it the hell off his desk.

Gun techs like expensive fancypants guns because they can establish a routine and follow it front-to-back, catching 90% of common problems and QC failures before they're even noticed just by following that routine. Techs don't like middle or low end guns (especially ones who have gone through a shitty rush-job spring swap before coming over the border) because the routine cannot be uniformly applied or relied upon, and tons of problems can just snowball so hard it's infuriating.

More than a few people will tell you to grab your pitchfork, and that may be justified, but if they are even offering to attempt to make you more happier it's a good sign. Good luck.

Edit: Re-read your post. Yeah. If you paid for extras then you get your gun fixed.
If they won't own it, they're being ding-dongs.