Have you talked to the IRS? Did they not tell you what steps you need to take for them to investigate?
If you can't get info from the IRS, you can try contacting the IRS Taxpayer Advocate Service for your area. They are especially prone to help if you have an economic hardship, or if there have been continued delays with lack of info from the IRS. At the following IRS website, find the USA map and click on your state, and it will give you the number of your IRS Taxpayer Advocate. If the Taxpayer Advocate can't/won't help you, ask them to transfer you to an an IRS agent. A couple of users reported that at least for them, that was a backdoor route to the IRS.
http://www.irs.gov/uac/Contact-a-Local-Taxpayer-Advocate
Also see this article for more info on how the IRS Taxpayer Advocate Service works::
http://www.irs.gov/taxtopics/tc104.html
