Poor customer service

I came to collect an order that’s been there since November. I’m coming from Alberton which is more than an hour away. First I try to pay with cash, the cashier tells me she doesn’t have change so I must swipe. I swipe, the amount gets deducted from back and I receive a slip which I sign for that says successful. The cashier then realised that her system is messed up and on her side the system says I haven’t paid. Then she calls the manager who then suggests that I come back tomorrow or I pay again and their accounts department will refund me after a few days. I then refuse because first of all I drove for over an hour to get here and there’s no proof that I will receive my money back after paying twice. We go back and fourth until he tells me I must move aside because they want to help other customers. I refused to move!