United Health Care Medicare Advantage Plans for Compass Rose review: Part b subsidy

I received a notice from SSA that my monthly benefit is being reduced because Medicare informed them that I do not have a Part B subsidy through my United Health Care Medicare Advantage Plan for Compass Rose. I am insured as a dependent on my wife's UHC/Compass Rose plan for Federal Employees/Annuitants which is supposed to provide a monthly Part B subsidy of $125. I have been enrolled in medicare and this UHC plan since Sept. 2023 when I turned 65 and have had the same policy with no changes through to the policy since then. A conference call between a UHC customer advocate, medicare and myself produced only finger pointing between UHC and medicare. After 6 calls to customer advocates at UHC I was referred to the medicare complaint dept. at UHC with a case number and the name of a representative that has been assigned to the case. I was given a general dept. 1-800 number but no extension for the rep. handling the case. I have left 6 voicemails over the course of a week asking to be contacted with a status update of the complaint and can get NO response back. I have filed an appeal with SSA and a complaint with medicare.