Open 24Hrs but we are closed.

My wife and I was celebrating our 32 Wedding Anniversary yesterday{4/9} and instead of making supper we decided to have KFC for supper. When we arrived at the KFC Mitchells Plain Westridge drive through the was 4/5 cars ahead of us. when it was a\our tern to place our order we where told that we could not place our order for 4 adults because they are closed due to a shift change. This is not the 3rd time this has happened to us at this KFC. What I cannot understand is they claim to be open 24Hrs. Does this only happen in Mitchells Plain or does it also happen in Camps Bay, Waterfront?