Deadlock all keys lost

HI, CAN ANYBODY PLEASE ASSIST? We have a Megane 3 Cabriolet 2013 model that is deadlocked with all its keys lost. Is there a way to override the deadlock in order to program a new key for the vehicle? The driver's door should be open at the time of programming but we can not get the door open, I have a feeling that it might not even help to get the door open as I understand that the computer is causing the deadlock. Please let me know if anyone experienced this?