Complaint - 2 months without response

I sent the documents to CPAM Ain on 09/01/24 and according to the AR was delivered on 10/01/24, I sent the documents as instructed by the English line de l'Assurance maladie (they sent me an email with a list of documents that I must provide for my registration – and I sent everything accordingly).
But on 20/02/24 I received a letter from CPAM which mentions that my dossier is incomplete with a list of documents that I must send (most of them I have already sent).
On 09/04/24 I resent all the documents are mentioned in the letter and according to my tracking number, was delivered on 12/04/24. Today (12/06/24) - after 2 months I called the CPAM English line and they mentioned that they did not proceed with my request because I did not send my pay slip (how could I send it if I started working on 01/04 and sent my dossier on 04/09 - does CPAM need a pay slip for 1 week?).
And my question is: why haven't I received any letter asking for this? They waited for my call 2 months later to mention that I need to send my pay slip.