Is photographing receipts that prove the company's right considered aiding in sin and aggression, knowing that the accounting department will charge the client a late fee in some cases? And what is the criterion for aiding in sin and aggression in this particular case?

You are not at fault for this work, and no sin will befall you if the department reschedules the debt and uses the receipts you photographed and collected to prove the company's right. Your knowledge that they might do this when a client defaults does not prevent the work, as long as its original purpose is permissible and your intention is not to assist them in that prohibited action. Their use of it for rescheduling is not intended but rather consequential.