Mortgage denied in underwriting

I was recently denied my mortgage in underwriting after being pre-approved. I work construction and have a base pay of 12.50 an hour and work a lot of prevailing wage work to bring my annual income over 40K and I have have a fico score of ~730. I told my broker this upfront during the pre-approval process. I was looking to buy a 80K house which was within my preapproved amount. Now they came back saying that they could only count my base pay of 12.50 and that I don't qualify even though my pay stubs and my w2's verify my additional income. My mortgage broker knew everything upfront so I feel like i got ripped off and have spent a lot of wasted time and money and the mortgage company isn't being very helpful in the situation and my broker wants to wait to see if I receive an expected promotion which would put me on salary pay however a negligible pay increase, which I didn't mention until after I was denied. I was just wondering if there is anything I can do about this situation. Thanks, David