My question involves business law in the state of: California

Hope you guy can give me some legal advices.

I have signed a contract with a Uniform company.
The contract would be ending in Jun 6th, 2009. But they have automatic renew the contract for another 5 years. I don't want to be with this company any more. They provide a terrible service and they have charged me for odd things here and there very month. I know on the agreement if I don't want the automatic renew contract I have to notify them at least 6 months. I did send in a letter certified mail stated that I don't want the automatic renewal but I will still carry out the contract till Jun 2009. I did send in the letter about 4 days short of 6 months (I sent letter on Jan 10th, 2009) because of that they have signed me up for another 5 years.
Can they do that? is that legal for them to do that?
If I don't want to be with them. Can I just return all the uniforms on Jun 6th and find some different company that provide better service?
If I go to court what is my chance of winning the case?

I have been with this company for years but I got so many problems with them. I have talked to 5 different managers to get problem fix but it is just like pulling teeth. I don't have time very day to follow up this. I just want to get over this contract with them and move on.

Thank you for your advise.