Burger King Paarl poor service

We've been in the drive-through line for 15 minutes, only to get to the ordering booth and being told that they closed. I think it's unacceptable that customers' time is wasted that way. If management foresee that all customers won't be served in time, there should be a cut-off so that customers don't join the line (like what McDonalds did). Behind our car there were another 5 disgruntled customers who waited patiently in line with the hope of being served.