Why must I be PUNISHED?

Just because my claim was dated incorrectly by the health care professional's secretary I am being punished for paying too much money. The claim was rejected because the date was postdated by mistake. I paid the professional a large sum of money, which was supposed to be reimbursed. Why does the company not accept a legitimate claim from a member? I submitted the claim on 1 September 2022 and the date on the claim was for 29 September 2022. I only checked with the invoice that was submitted to see what happened. It is not fair on me if the mistake was with them.