Dimuntion of Value-Third Party Ins in MD

Accident occurred in Maryland in Dec, 2000. Other party at fault. Injuries being handled by a lawyer.
Our '97 Acura CL was repaired by a body shop in which numerous hassles occurred, including the ins. company using aftermarket parts without telling us (we found out and they reluctantly replaced the part). The car has been repaired and we took it to get an apprasial because my wife wants to sell the car. Multiple shops have offered us substantially less money since the car was involved in an accident. We called our insurance company and they said to file a 'dimunition of value' claim with the third party ins. co (Selective), which we did. We just got a call from a Selective Rep that they will not pay on the claim, the rep said we need to show them Maryland case law.. Maryland does NOT have an exclusion to dimunition of value in their laws and the Selective policy does not have one either.
What should we do now? We are going to file a complaint with the Maryland Insurance Comission and were thinking of taking this to small claims court if this is a feasable option? The dimunition of value is around $3000 and small claims court in MD handles up to $2500, better that than nothing if that would be the best route.

Thanks,
Eric Sumner