Rent payment not allocated and not fixed for a month

Terrible terrible service with weak controls in place. We’re approaching a month now since they sent have handed over my account to debt collection for rent they don’t want they did. I have submitted all my POP and even went to the extent of sharing my 3 months bank statement to show the rent was paid and they still have not allocated my payment. I have following up on the matter for weeks and the guy responsible for my account is never around and barely even responds to WhatsApp messages.