Don't understand

I recently needed some specialised work which is quiet urgent the quote from dentist which was the lowest one I could get was 32,000 I was prepared to have to pay about 10,000 out of my pocket. When I phoned for authorisation was told sorry only 5.000 is available this is my first visit to dentist this year so I went to their website and onto my profile which says there is 22,800 available for specialised dentistry after umpteen emails and calls they stick to the 5,000 Why are the call centre agents saying one thing and info on web is saying another