Reliance Standard keeps putting off their decision on my STD/LTD claims with them.

I filed a claim for STD/LTD with Reliance Standard in late June, at my SSA attorney’s advice I filed for SSDI at the same time. Reliance, after two “complementary” checks for early July has been investigating my STD claim since. We have now passed what would be the effective date for my LTD, my SSDI has been approved (9 weeks), and calls to Reliance result in repetitive lip-service about unreceived documents. I pointed out that they have received the same documents as the SSA, and was promised a return call from the investigator. I won’t be holding my breath. Any advice on how I can at least get the complete term of my STD (90 days)? They haven’t denied anything, simply haven’t done anything.