Bad service from debit card dispute specialist

I went to shoprite on the 18 March to buy certain things which cost me R224.95. When making payment I used the scan to pay on the app so that I can accumulate points, payment went through as it is shown on the bank statement but an invoice was not generated, so shoprite it's like payment didn't go through and the cashier said if it went through the bank will reverse it, but I had to make another payment using a different method of payment. So I inserted the card to pay and an invoice was generated. But in all I double paid for a single transaction. Went to shoprite with my bank statement and they told me to go to my bank. I went and reported the matter and gave them the bank statement showing that a single transaction was paid for twice. Now the so called specialist has finalised the case saying that there are no irregularities and my account will be real debited with R224.95 again. How does a specialist come to this kind of conclusion when it is clear on the bank statement provided that a single transaction was paid for twice, what kind of specialist is working at FNB what experience and credentials do they have if they are unable to see from the bank statement that a single transaction was paid for twice.