Nandos appalling service

We ordered food at Nandos Gold Reef city at around 20:00 this evening. We waited for almost 40 minutes whilst observing the waiters attending to people who had ordered after us. Well I eventually asked one of the trainees to call their manager , who was somewhere in the back. It was only then that we had almost the entire staff rushing to check our receipt and when the manager "Musa"arrived. He didn't even greet, nor introduce himself, he just exclaimed to his subordinates saying " it's Matron's order, we misplaced the receipt. They then turned around and disappeared for a further 10 minutes. I asked my kids to stand up and we left. I asked for a refund and it was given with a remorseless apology. I am extremely disappointed in the service I received today and I think every single one of your staff needs training. I felt very unwelcome as though I was invading.. I am a regular Nandos customer but I honestly had my worst experience... They wasted my time, mind you it is a school night .. it now gave me a task to go and order elsewhere and wait again while being nagged by hungry kids... I'm not happy n it's really appalling service.