Double charged

Went to their store on 29/07/2023 at Thaba Nchu Free State ..i paid and it was said the transaction did not go through and they said i should pay again it will reverse back to my account,and that i am not the 1st client that it happens to Imagine paying twice for one transaction. And they said i should come back with the bank statement on Monday to check if indeed it did not go of...such an inconvenience and unnecessary costs..and The cashier and the "supervisor did not show any remorse. They kept on blaming the system .Imagine if i only had the amount for the first transaction