I need to know if my husbands job is allowed to take away labor hours?

my husband works for a car care company. The manager recently told him that when he cant get a customer to agree to the work needed to fix there car, he will cut the labor time it calls for so that he can get the sale. So if the computer calls for 3 hours labor the manager is cutting it down to 1.5 hours labor. This wouldn't really be that big of deal except my husband gets paid more if he brakes base, but he cant brake base if the labor hours are cut. So i need to know if they are allowed to do this? My husband at one time used to manage that shop and was not being treated fairly so he ended up quiting and they recently called him and asked him to come back. I have in the past called wage and hour on them for shorting him on his check for a holiday. he was getting paid salary and the week for the holiday they changed his salary amount down 100. so he didn't get paid for it. They ended up having to pay it back to him, I really just need to know if this is legal and if not where can i call to complain? please any help