Poor service claims consultant

My mom had an operation in April 2021. She spent almost one month in ICU. For the past 3 weeks we have been trying to get Momentum to settle the anaethetist’s account. Momentum has repeatedly confirmed that they paid the monies into my FNB account, R12 343, they failed to provide me with a claims summary confirming the amount and account details. An amount of R6666.90 which was part payment of the anaethetist account was paid to me for which I received a claims summary and happily transferred the money to the doctor. Momentum cannot provide the same claims statement for the R12 343 which they insist they paid to my fnb account . They now want me to provide my bank statements. The doctors account dept is now wondering whether I am withholding payment. In the midst of caring for my ill mother, my sister and I are following up daily with Momentum consultants, to no avail. Please help resolve this matter.