Need Advice for Issue with Dropping Previous Insurance

Hello. I've got an interesting scenario that I'm hoping you can help me navigate. I moved from PA to NY for a new job in September of last year. I got health insurance (HSA plan) through my employer and figured that would be it. I got my flu shot at the end of October in PA because I was back in the area and it was still in network and should be covered by my own insurance. Fast forward to now, my new insurance has denied the claim for the shot and informed me that I am still covered by my mother's insurance.

I have had my new insurance set themselves as primary in their system which should cover the flu shot bill but now I am stuck with secondary health insurance that I no longer want or need. Additionally, to my knowledge, I cannot contribute to my HSA if I still have additional health insurance. I have 2k from my employer (1k in both 2023 and 2024) as well as another 1k that I contributed in 2024.

I spoke with my mother's insurance and they informed me that because it was passed a 60 day limit, they cannot remove me from the plan due to IRS rules. Open enrollment for my mother's plan is November. My own insurance was suprised and offered to send a letter proving I was insured but ultimatly could not do much more. Can I really be held hostage to health insurance that I no longer want or need? Is there anything I can do to remedy this or am I stuck with additional insurance? Thank you in advance and mods please update the flair if I picked the wrong one.