Is there anything I can do to have my property taxes lowered.

I was told before I built my house by our county assessors office that my property taxes would be around 2400.00 a year. I have been in my house a year. I recieved a notice that they would increase to 6000.00 now that I finished my house. Both my neighbors have more land and each has 2 houses and detached Garages and out buildings. Their taxes are 1800.00 per year. I called and compained and they sent me a notice that my taxes were lowered 300.00. This was after they told me the only way to lower thenm was to get a appraisal done on the property. What can I do.