Unfortunately, you'll have a tough road ahead of you. A shipment that shifted in transit could be caused by two things: the freight was not packaged properly to stand the rigors of shipping or the transit experienced a situation that was outside of the expected norms of shipping. If it didn't stand the rigors of shipping there was not enough shrink wrap, the carton boxes had too low crush weights, the freight was not stacked properly, different sized boxes on top of each other, skids that couldn't handle the expected weights etc. If it was packed properly then you have to identify what would be out of the norm of shipping. Was there an accident, was the freight cross docked improperly, was there willful damage?
The insurance company has an obligation to give you a claim number and a decision on the freight. It may take a while, but it is their obligation. If the amount is below the deductible the insurance company should make arrangements for proof of payment from the carrier or to choose to pay it and collect from the carrier. You need this process completed so that your client can dispose of the freight and not have it sitting on their dock forever while it progresses. If you are not getting anywhere with the insurance company getting a claim number, then ask them for a letter on letterhead that they will not provide the claim at this time and state the reasons. All this information you will need if you choose to take this to a legal level. This claim is $1500. The likelihood of this going to legal is very small and the carrier is banking on it.
From the very little details provided I can almost guarantee that they will claim that it was not properly packed and shifted under normal transportation. Your customers choice will be if they want to get a lawyer involved to proceed with legal action to recover their damages in SCC. It is a large burden to prove because the carrier will never tell you if their driver drove through the median or a similar accident. This is something your lawyer will have to investigate and have proof. You then have to get technical proof, the carton crush values, skid data, amount of shrink wrap etc, and that all aspects of the shipment met or exceeded the requirements for shipping.
Good luck.