BCBS PPO Out of network

I was approved via the bcbs inquiary dept of Wisc. As I have bcbs of mi going to wisc is considered out of network! On Sept 28 I was told by the hospital my ins said I was not covered for them! The Surgeon had an approval letter in his office so I was very confused. Found out the 29 that the hospital had called the wrong ph. number. They had called the number on my ins. card. They have to call BCBS of Wisc. As thats who will be billed and then they will bill BCBS of Mi. I went for Pre-op tests on the 1st of Oct and everything was fine. I;m still not sure about the anasteologist m/s they have a contract with Wisc BCBS but said not with Mi. So I figure I might end up with their bill to pay. Unless its worked the same way as the Surgeon and Hospital's billin. Hope this helps someone.