What could I do if there is no contact with a company after sending a product back for warranty work?

I purchased a product from a company and the product came with a warranty, within the warranty period I had an issue and contacted the company. They offered to fix or replace the product, as outlined in the warranty, free of charge and I just need to cover the shipping cost each direction, again this outlined in their warranty information. I shipped the item to them on 4/12/2015 and according to my tracking number they accepted delivery of the item on 4/14/2015, I have since sent them multiple emails, and left multiple voicemails requesting a status update as when I spoke to the company owner prior to sending the product back to them he stated it should only take a few hours to fix the issue. Later this week it will have been a full month and I have yet to hear any sort of update and they are not answering emails or phone calls. This product is part of my vehicle therefore taking it off and sending it back to them has left that vehicle unusable. What can be done? Is this something that I should get the law involved with? If at the very least can I have the police run by and see if they are still alive? Any suggestions would be greatly appreciated.