Can't trace my payment apparently

On the 21st of April 2024 I made a tax and duties payment to buffalo logistics for a shein parcel. I failed to notice the reference code that I was supposed to type in when making the payment. However the payment was made into their account and after numerous attempts to send them proof I am still being asked to make the payment. How is it that they are unable to track the payment from their bank account. Today is the 29th of April and they still can't find the payment. If someone told me he paid a certain amount of money into my bank account on the 21st of this month I am sure I will be able to trace the transaction.