Just want to say thank you to everyone for their input. It turns out I don't have to wait for the lights to go out, this morning I unlocked the car, opened the back door (the one behind the driver), put my 3 yrs old in his seat, strapped him in and shut the door - the car auto locked itself with my little one in there. It is a massive safety issue, especially with the current heatwave but also in general. I am very disappointed with both, RAC and Octopus, as they both claim it was a human error and will not return the money I paid for the locksmiths. Be careful out there with your cars.