Poor service

We went to KFC Lhp last night as they are 24hours branch. When we got there we stood in line to order food, we then wanted to us the bathrooms and they were locked, when we asked about the key the staff were rude and stated that the key was with the manager. We phoned the manger and they kept passing the buck. This took more than an half an hour upon when we returned to the line we were in the exact same position as the line didn't move due to the poor service. Why were they understaffed when they know it's month end and that there will be a lot of people coming in and the other thing is where do the staff to to use the bathrooms if they were locked? As a patron I feel that we didn't get the quality of service that the kfc brand has created.