I also think talking about this with your T will help, even if it doesn't affect the insurance company's decision. I wonder if this feels punitive in some way--like, if part of you wonders if the T had a role in taking away the second session due to your disclosure. That's the kind of fears my mind jumps to, and sharing that with your T can really help.

I do think it's odd that the decision to stop coverage was made in June, unless your insurance operates on an academic year schedule. If it works on a calendar year schedule, usually coverage changes are implemented in January.

I hope you are able to have your feelings on this heard.