Son opted out of uni insurance in 2016, but wasn't refunded. Student union and insurers are blaming each other. Who's liable?

Question

Daughter graduated at a univ. in ON Canada in 2017. Each year that she attended, she opted out of the student union (SU henceforward)'s health insurance as mine covered her. SU confirmed each year they got ALL her opt-out requests.

She chased SU for refunds in 2018 but they just stalled her. Because she's been too polite and I don't want this to worsen her suicidal ideation, I'm taking over. I wrote the Uni President in 2019. THEN SU replied

We can't refund you just because we have no record of you getting an opt-out refund. We don't handle refunds or collect proof of refunds for our health plan – We just handle the receipt of opt-out requests, and forward them to the plan liaison. Insurer 1 was the insurance liaison that had to retain proof of the refund. If you already got refunded, we wouldn't know, just like when current students ask for opt-out refunds. We have to rely on Insurer 1 and when we asked for you, they replied that as the account has been closed, they can't prove if you got refunded or not.

Insurer 1 replied

Your student union would have refunded you. But we no longer administer the plan, and we sent all of the refund information to the new administrator. They are responsible for retaining it. We can no longer access the bank account where the funds were withdrawn anymore, so we cannot know if you got refunded or not.

Then I emailed Insurer 2, but they replied

Insurer 1's answer is wrong. We never got records of opt-outs before we became the new administrator. There was no reason for anyone to provide us that information. Insurers just receive information on students covered by the plan, not students who have opted out.

My questions

1. Is Insurer 2 correct that insurers "just receive information on students covered by the plan, not students who have opted out"?

2. Insurers 1 and 2 are saying opposite things. Who's correct?

Answer 1

Student union and insurers are blaming each other. Who's liable?

The student union is responsible for refunding your daughter regardless of the union's arrangements or decisions as to third parties. For it to be otherwise, your daughter (or whoever made the payments) would have to be duly informed prior to being enrolled in the union's insurance plan.

Is Insurer 2 correct that insurers "just receive information on students covered by the plan, not students who have opted out"?

Insurers 1 and 2 are saying opposite things. Who's correct?

Both issues are inconsequential to your daughter's right to reimbursement, and would require knowledge of the agreements involving the insurers and the student union.

As a side note, the response by Insurer 2 seems reasonable except for "There was no reason for anyone to provide us that information". The fluctuation of the number of exposures (and impliedly the opt-outs) in a group policy can be of interest to a prospective insurer for purposes of rate making of the plan being assessed. That fluctuation is likelier to be reported as an aggregate, although the prospective insurer might as well prefer records on an exposure basis.