duplicate orders due to in-app errors

I was sent two duplicate orders at the same time. I spoke to the helpline, and they told me they refuse to refund anything.

The 60/60 app gives you an option to update your order before you pay. I updated the order with a single additional item and it created two full separate orders which it charged me for. When i told the second delivery driver I didn't want the stuff as it was a duplicate, he refused to take it back with him.

Helpdesk told me they know about the problem with the update button on the app creating duplicate orders but apparently they dont care and they just refused to sort anything out.