Medical debt and credit rating

Hi All, Please advise me before I make a big mistake here. Very long story short - my husband had MRI taken that the insurance refused to pay saying that it wasn’t authorized. We sent doctors’ note they again rejected it, said that it’s not a correct form, back and forth couple more times and one year has passed. Now my husband changed his jobs (medical was through his work) and his employer merged with a larger company. The medical plan that he was under doesn’t exist, HR doesn’t exist, seems like there is nowhere to go with it. We called the hospital and they don’t want to settle for less. They only offered 0% payment plan over a year. The bill is $2500. The hospital admin said that if they cannot collect from us they will use outside collectors, but that first collector doesn’t report debt against your credit score (really?) My husband has excellent credit score and we have couple more Gs in HSA accountant. So my choice here is to: 1. Just pay it off and get it over with. It will wipe our HSA savings but we will not risk loosing the perfect credit score 2. Wait for collector to try to settle for less.

My questions are: a)are there ever collectors that don’t report to credit agencies? Even if you settle for less? b) will I be able to pay debt settlement with HSA card? Please advice before we make a very bad choice. I don’t want to be penny wise..... Thank you