It is difficult to say solely on the information provided whether or not you have a case. In general, if your car was insured, and it was in fact stolen, then the company has an obligation to pay (the payment may not equal the amount owed). Some companies, such as Allstate and Liberty Mutual are advertising they will buy the same car or year newer if your car is stolen, not a 2013 or 2014 model.
You might write the Department of Bank and Insurance prior to trying to sue.
Your insurance agent, unless you use GEICO or another company with no agents, such as The General, and 21st Century, should be helping you with this claim.
If not, I am certain there is a young attorney who is willing to take on the Giant insurance company. Remember, as long as they have not paid, they are making money on the premiums you paid.
Best of luck! I am sorry for your aggravation.
The foregoing is not intended to be legal advice upon which you may rely as I have not been retained for this purpose.
If your claim was denied, and you are unsatisfied with the reason, you should hire a local attorney to dispute the denial. That's the long and short of it.
As to the specifics, there really aren't enough facts to give detailed advice. That's something you're going to need to discuss with that attorney.
This answer does not constitute legal advice and does not establish an attorney-client relationship.
As a general rule, it is not fraud for an insurance company to deny a claim. It may be a breach of contract.
If this answer was helpful, please mark it as helpful or as a best answer. This answer is for general education purposes only. It neither creates an attorney-client relationship nor provides legal guidance or advice. The answer is based on the limited information provided and the answer might be different had additional information been provided. You should consult an attorney.