Got lots of time to waste order Nandos from galleria mall guaranteed waiting time is one hour

Went shopping in the mall and then as always I take the kids for a meal before we head on back home,so for the second time I take them to nandos and offcourse we get there as expected there's a long queue and one cashier,I should have left on the onset nevertheless I stood .My turn came to order and ordered a family meal which I won't mention the cashier told me waiting time was half an hour so I said no problems,the half hour arrived there was no food served I waited just ten minutes to the hour so I approached one of the ladies and requested our cold drink which she delivered and five minutes later brought our food so in essence we waited an hour ,this is the second time I've got bad service last year was the drinks they had inclusive of the meal which ran out leading to me paying extra for something they messed up on and this year the waiting time,they need to plan properly