Claims Nightmare!!!!!!

The worst service ever. My daughter was at the orthodontist on 11 Sept 2018. I paid out of my pocket. On 13 Sept 2018 I sent my claim to Denis. I resend the claim on 12 Oct 2018 and did the same on 7 Nov. On 14 Nov I called the customer care line and I was told they did not receive my mails. After going back and forth, suddenly the say they did receive a mail but the statement was unclear and I need to send it again. So I send my FOURTH mail on 14 Nov. Today, 23 Nov, I phoned again and AGAIN was told that they received nothing. I cannot beleive this. On Monday my daughter gets her braces and I need to pay an enormous amount upfront. How am I ever going to claim it back from Denis???????