Insurance Question

I had Blue Cross Insurance in Feb 2007. I started my 6 mos pre-op diet at the same time.  My husband suddenly lost his job in March.  My new insurance has a WLS exclusion. I chose to pay COBRA for myself to be sure that my surgery was covered.  So now I have United Healthcare and BCBS insurance coverage. I planned on using BCBS to cover the surgery and then drop COBRA once it is over.  I was told by United Healthcare that if there are any complications or problems that require medical attention after gastric bypass, they will not cover anything that could have been caused by wls.  I think this is crazy. I thought that I could pay for COBRA until the surgery was over and then use United Healthcare for any post-op visits, bloodwork or prescriptions.  UH claimed that if the billing code was related to obesity of any kind it will be denied of payment.  Is anyone in the insurance business?  Can you help me???  I have always had medical insurance through employers since I've been 18, no gaps or pre existing health problems.