Exchange plan is unfortunately probably your only bet. We looked at group insurance through United and Anthem and neither were affordable. Looked at a chamber of commerce plan as well, better than others but still a bit high and would likely have gone higher with underwriting. Then we went to the exchange, rates aren’t great but there was at least the possibility of subsidies.
Health insurance options are probably the worst part of owning a business.
With regard to fixing their mistakes, poor bookkeeping or perhaps they wanted to let the funds settle before refunding to ensure you weren’t trying to scam them.
With credit only, maybe they are wanting extra protection from a credit transaction versus a debit transaction.
Does seem odd to me though.