Cancer surgery coming up

My wife has surgery for her cancer this week. It is to remove a deeper section where a cancerous mole was recently removed. Our insurance said they will only cover $600, leaving us with $5000 to pay out of pocket, Plus the aftercare expenses. We tried to work out a payment plan to no avail. We have been trying to schedule the surgery for 4 weeks now, and now they inform us that we need to pay in advance.
It has been an emotional roller coaster for our family since we found out about her cancer, and now we face this hurdle.  any assistance will be greatly appreciated, and for all we know, could be lifesaving. Thank you for your kindness and consideration!