No staff at a drive thru, no explanation offered a

Staff not available at a drive thru. We went to a kfc in newlands to purchase a meal, but when we drove through their drive thru there was no one available to assist us. We waited for over 5 minutes and hooted but still no one showed up. Both my husband and I have medical conditions that restrict us from walking in and stand in queues. When we eventually drove 5 the next windows at collections, a staff member ordered us go inside if we want to buy food. If there was a problem with their drive thru, they should have place a sign to save customers from waiting for a no show service. <br> We we then forced to go to another kfc branch just so that we can get a meal without having to jump off and stand in queues. I'd really appreciate for someone to explain why were we treated that way.