2004 Chevy Trailblazer rEPAIR cOSTS

I just had to have the Exhaust Manifold replaced on my Trailblazer. I received an estimate of $490.00. While there I told them to do an Inspection. She called and told me that I needed brakes and rotors on all 4 wheels. I asked for an estimate and I was told $537.00. So that is like $1027.00. When I got a call today that my car was done I was told that the bill was $1,577.13. I was SHOCKED. I asked for some info ono what happened. And told them I would be there for an explaination. I was very very upset that I was not notified when more work was needed. When I got there I said "How can I have to pay $500.00 more than the 2 estimates?" I was told they were just estimates. I understand that it could always be more however that is a bit excessive. I was told I needed a ball joint and extra labor there so they just did it. Which added about $200.00 onto the brake job and the rest added onto the Exhaust job because of needing all new pins (or whatever). My question, Don't estimates mean anything? Is there something to be done here?