BAD DRIVE THRU SERVICE

I've been going to Kuilsriver branch 4 time now and all for time I had to go and wait in the parking lot and wait for my order. It is not a 5-10 minute wait is 20+ minutes wait. I requested to speak to manager today as I was no about to wait another 20+ minutes in the parking lot again for a Latte for only it to be cold. the Manage ( Janine) advise they only have 1 Barista and 1 coffee machine and the Barista first needs to help the people in the Mc Cafe before she can assist in the drive thru. I told the Manager they need to advise their customer's when order @ the Cafe there is a waiting period to avoid customer frustration and her responds was "OK" not even a sorry sir. BAD BAD SERVICE....I wish I can give them a 0