Unprocessed refund

On 29/04/2018 i booked a flight ticket and for some reason i cancelled it using capitec debit card. Flight booker sent me proof that they have refunded my amount on 15/08/2018 but capitec has not still processed it and credited in my account yet,. I spoke to Ms zanele and provided her proof of credit note via email but she hasnt come back to me till today. The reason she gave me is they cant find original transaction. I provided them with specific period of transaction. My concern is why they not following up with clients the status of query? How they cant find original transaction? I must be having hardly 5 transactions on that day. Isnt it incompetency or negligence by bank to client? I was in indeed need of money last week and was relying on that money but it never came back till today.