Unowned debt in collections

It's a long story so I'll try to summarize. AAA auto insurance was paid upfront more than $300 for an insurance policy in 2008. I recieved notice that underwriting didn't like some of the specifics of the policy and cancelled it after less than one month, after which they owed me money which I never received. Months later they bill me for over $700 for an insurance policy. I called someone up and explained the situation and was told it would be taken care of. Now, in 2012, I just found that they put me into collections back in 2009 and never received notice. I haven't been contacted by any collections, I just found it on my credit report. Is there any way I can get this resolved, and who would I contact? Would collections even be interested in the fact that they're trying to collect what I believe to be an accounting error?