We often had to go through either the insurance agent themselves or the company that manufactures them. Often they will have programs for people who cannot get insurance coverage and then either give it at cost or give it to you free. There is generally paperwork involved but no more than you would normally have to do.
Coloradogal is on the right track here - see if the manufacturer will send you their description of the items, and ask them if they consider or describe them as disposable. They may even be wiling to intervene on your behalf by contacting the insurance company directly.
Insurance companies rely on us to be too busy, tired, or complacent to keep arguing for the coverage we are paying for.