I have low potassium

Well my surgery is scheduled for Wed. but I went for lab work last Wed. and they said my potassium was dangerously low. So I went back the next day and they redid my blood test and said it was up a grunt but still way too low. I am supposed to go back tomorrow and see if it has come up over the weekend. If not my surgery will be postponed. Then today I find a letter from my insurance company saying that they will not cover the surgery because my doctor is not a preferred surgeon. I am starting to feel that Im not meant to have this surgery.