"Given false hope of treatment"

As an active person and having spent the last 6 months not able to walk or drive very far because of a torn knee ligament, I was finally referred to an orthopaedic surgeon but told the waiting list was 18 weeks. I was therefore delighted to receive a letter offering me the opportunity to be treated earlier in the private sector with no cost to myself or at another NHS hospital. I phoned the number given immediately to say that I would accept this. However, 2 hours later, I received a phone call to say that the letter should not have been sent and I would be referred to the NNUH. Why was I given false hope and when can I expect to get my mobility back?