Unfair Exchange Rate Policy

Hi.<br> I have bought a cellphone as per attached invoices. At around 14h00 today. WITHIN LESS THAN AN HOUR I came back with the intention of exchanging for a much higher/upper model in the same store (having realised that I cannot perform my banking app) and I am told that it is impossible. The phone's value is R499 and I am willing to add a difference to buy a phone for R899. I think the timing should have allowed some flexibility and exception. I have spoken to the Manager in the store and he washed his hands based on internal policies.<br> <br>