Manual unlock without key - MINI security issue

I have a 67 reg MINI which I park on the road (we don't have a garage). In the last couple of years, I have gone out to my MINI in the morning to find the doors unlocked, and sometimes ajar.

I use an RFID wallet for my keys inside the house, but I have since discovered that people are able to jam a coat hanger (or similar implement) in between the door and the interior which pops open the unlock latch - there are some scratches on the inside which indicate this. Worryingly, since the car is then unlocked, the alarm doesn't sound.

Has this happened to anyone else, and is there a way to sound the alarm if the door is not opened electronically using the key?

Thanks in advance.