Closing the store before time

It has happened again. This time I was really surprised, I got to the store at 18h30. The manager Mike was standing at the door. When I got to the till to pay for my goods, this was at 18h49 the roller door was closed and manager had left. I repeatedly asked the cashier (I didn't take her name) what time the store closes and she she confirmed at 19h00, I then asked why they closed at 18h49 and where's the manager as I need to querey this, she said the manager had left and he had instructed the security to close the door. I then said this is totally unacceptable and I am going to report this. She said they are also tired and that's why Mike has left early. I mean no. 1 this is abuse of power and its misleading of consumers, how do you advertise the store closes at 19h00 and you close 18h49. HeadOffice interevene so thjis can be sorted out as this is not the 1st time.