change the filter, dissinfect the entire AC system, and run the dissinfectant through on a monthly basis. Keep it on fresh air and you shouldn't have a problem in the future.
Until the mold and mildew is killed, it is going to be odorous.
give it a try yourself. It's cheaper than going to the dealership.
To make you feel not left out, many modern car makers are having this problem.
Once the mold and mildew set up, it is hard to get them out, but it is do-able.
steviej