It was never used, if it was something else I would understand, but this is an engine. You will be surprised that depending on the situation, some people have too much pride in their work and will fix an issue like this just to keep a good reputation. (They might not cover 100% and there may be other compromises, but it's better than nothing.)
If they don't fix it, document everything, take lots of good photos and give them a negative review everywhere. If they f**ked this motor job up, who knows how many more they did?
Also, contact them via telephone.