Appalling service rendered

IM at my wits end, I am paying for something i not getting! and this is frustrating me big time, on the 13/01/2021 the scheme was sent a quotation for my sons braces, this quotation was approved on the 15/01/2021 i sent thru this letter to the scheme and even called to ensure all is in order, I also had a team leader call me and explain to me everything i was unsure about. On the 1st of Feb my son started hes treatment, a claim was put thru and it was declined. I then sent a email to your complaints department on the 5th of Feb , to date i haven't received any feedback on the complaint, now I have been getting emails and SMS to say i need to pay the money over to the provider, yet I am paying for a service, no one at your call centre can tell me why the claim was not processed even tho a approval letter is on the system.