What happens if you see the fine print only after the job is done?

I hired someone to core drill a hole through a 1 metre steel inforced wall that used to be a bank vault. He said the job was straight forward and would cost $242. The job took 8 hours as the drill kept breaking down and had to be fixed plus the water pump was not working properly and flooded the place. On top of that, as the contractor was putting his gear away to leave he accidently pressed on a can of yellow aerosol paint and it went all over the vinyl that had just been laid the day before. We have tried removing the stain to no avail. The job finished at 2am and I signed the site form stating what had been done. Only after reading the small print the next day did I find a clause saying that all quotes are subject to change. They now want over $1000 for the job. Do I have any legal rights considering this paper was not given to me until after the job was done?