Richard Denzer Construction review: They have spent huge amount already, but the work has started recently

My friend introduced me to Richard Denzer Construction. The owner told me that my reconstruction of the house would take 8 months and it would cost me 10k. I have paid 70k already, but the job started only 2 months ago and they didn’t finish the first floor yet. I was shocked that they have spent huge amount of money. I have decided that I want to stop the deal, but on the other hand it isn’t very wise.