Left with a shortfall of R70k

I had a surgery on the 04th of October 2018, I used a doctor at sunnighill hospital which is not a preferred provider, that was explained to me when I called for the authorisation, this is one of the best neurologist and my operation was a success. To my surprise discovery did not even settle half of what this doctor claimed, after a surgery busy recovering now I must worry about a bill of R70k I get that the doctor is not preferred but can the medical aid really only pay a drop and leave me with the rest. I must now pay a bill for the rest of my life, no one has R70k lying around. Please ask all questions before going with discovery medical aid. We pay an arm and a leg still not to get all the cover we need