FNB lost payment

My husband has had a credit card for many years. I always make the payments into the credit card. In April I made the payment of R1600 into it but paid from Capitec. Unfortunately when I set up the account on my banking app there was an account number. I made the payment into the account but it never reflected. I contacted Capitec they said the payment was approved on their side. I contacted FNB they said they will follow up. My husband phoned FNB they said e mail the details through they will transfer it into the credit card. Then phone calls started because no payment was made I explained the situation and they gave me a different email to send proof of payment to. It is now a month later and there is still no payment or communication from them. I would like someone to help please.