Ok now I get the situation. Your English is hard to understand and the terminology your using is inconsistent. I can see why they may have had a misunderstanding and got lost in translation.
You want a European skull mount.
I do not see any holes in the photos that were drilled. Those are holes that connect tissue to the brain and eyes and mouth etc etc. those are natural from what I see in photos.
If you came into my shop and asked for a SKULL CAP. What you have is exactly what you'd get. Just the cap. When I take in sheep,goats,antelope and someone wants a skull cap reproduction you get just the skull cap. So you can use it for a shoulder mt or life-size.
Now if you had asked for a beetle cleaned skull and a skull cap reproduction then that's a different story.
These large shops ,your rarely talking to the people that actually do the work,your talking to a receptionist or book keeper.
On another note. What you see with the discoloration is what's called "the boss " it's the same with cape buffalo . It's the growth part of the horn. They always needs epoxied and painted. It will always discolor regardless of how it's done .
To get a Reproduction skull that'll work and fit is gonna be a lot of time and money. You'd need a skull that's close to size. So buying a new skull and then molding and casting the new skull and then cutting out the casting of the new skull to fit and epoxy the old horns on.
I'm not sure what prices they quoted you . But at minimum if someone brought me a musk of skull to be cleaned and then also to get a nice high quality cast job. You'd be looking at minimum of 3500. The amount of silicone and urethane and painting would be a week or two of work . So if you do go again and looking at getting same work done . And for other people that might be reading this post . If it's less than that cost ,your probably not on the same page or something's off.
Now if you wanted more castings then it gets cheaper because the mold is already made. It's a matter of urethanes cost and painting and time. Most of the cost is in molding itself .
I wish you luck .
The best thing to do to cut your loss is just get someone to epoxy and paint the boss and put it on the wall plaque or make a pedestal for the table with it.