Fnb and Ismail & Dahya, allocate my payment urgently

I have a loan with Fnb that was handed over to the lawyers( Ismail & Dahya) so since June I have been committed, paying them what we had agreed on. The payment method I use to pay is an easypay number as my reference. That I pay at any checkers or pick n pay stores.

So everytime I pay,I would take the slip and send it to the lawyers via whatsapp so they can get proof of payment. On the 22 November 2024 I paid R1100 using the same method but this time, for the first time my payment is not received, I've double checked the reference number, it is correct. I've called the lawyers, they tell me that they are waiting for Fnb to allocate the payment. When I contact Fnb, they say they can't allocate payment. As a client I'm left confused. I don't know what changed comparing to the previous months. How do I continue making payment if payment will not be allocate