Blue Cross Blue Shield

I am in the preliminary phases of getting insurance approval. My plan does cover WLS, but of course I have to meet certain criteria of which I do. The problem is that I have contacted several doctors who have told me that Blue Cross Blue Shield approves the procedure but in the end absolutely refuses to cover any more than 8 to 10 thousand dollars. With that in mind I am unsure as to what I should do. I called the customer care department and they seem to think that it has to do with whether or not the procedure is done within the network or outside of it. Whatever the case is their anyone who is either going through or have gone through a similar situation?