LACK OF SERVICE

I have written to Denis 3 times without success about payment of a filling done. I need to have a bridge & crowns done to stop 2 left molars deteriorating completely. My plan states I am allowed 1 crown/bridge per year per family now after being with them for over a decade don't want to authorise payment on the quote for crowns/bridge to avoid more deterioration of my 2 left top molars. Stating waiting periods for fillings on said 2 molars must be 720 days how ludicrous is this? Now I had a filling which has been done 600 days ago what must one do. I am SASSA pensioner so do not have shortfalls.