My question involves collection proceedings in the State of: California

I have paid for my home association fees for the past 20 years without a hitch through autopay. Because of a change of the management company, my autopay did not go through. As I don't read my snail-mail for notices that must have been sent to me, I did not realize this was happening until I received the first collection letter charging a $500 "collection fee" for the $800 owed. My efforts to have the management company withdraw my case from the collection agency was denied by the board and now I seem to have to pay the hefty and excessive collection fee to have this matter resolved (or otherwise I could hire a lawyer and sue in court which I'm not about to do). Note the fee was for having sent me a letter or two without even calling.

My question is, is there a law against excess collection fees charged? If so then I'd plan to pay it all and then sue the collection agency in small claims court. But if there is no such law, then what is there to prevent the collection agency to charge whatever at their pleasure?