Liable for a benefit which Discovery did not cover

Can Discovery Health stop wasting my time. 3 queries was logged with regards to my dental benefit being depleted even though no monies was paid to the dentist!! I have queried this multiple times. After constantly following up and wasting airtime, they get back to me with the answer that 'Please note that your limit was used correctly as member is liable for a co-payment of R165.00 for the procedure code 8109'. What kind of answer is that?? How can I be liable for a co payment but ZERO was paid to the dentist. ZERO!! it even shows ZERO on your app and website. So please tell me why my benefit is depleted and I am liable for a co payment when Discovery paid ZERO to the dentist. So you telling me that I have to pay money for something that discovery didn't even cover?? Is this how your benefits work?! After 3 weeks I get am answer like this that doesn't even make sense. 3 weeks just to give me such answer that holds me liable for a claim?? Is this how you treat your clients?? How much more of my time is discovery going to waste with this. Please answer me why am I liable if nothing was paid out of this benefit