4 month waiting period - Not kept up to date on progress

Renasa`s client drove into us on 16 April 2024. Our claim is outside the turnaround time they provided, we had to keep on following up. Quest blames Renasa and Renasa blames Quest. Our claim was supposed to be settled on the 11th of July, I had to follow up and now and only now they sent me the settlement today. I am expected to wait another 30 days for payment. So in total I must wait for 4 months? how is this treating your customer fairly?