My central lock starting acting up a while back, didn't bother me much since i rarely lock it

Now i want to get it fixed, problem is that when i lock the car using key or my alarm to do it it will auto unlock again, so i have to lock it by holding the key in locked position a few seconds.
I guessed that the drivers door actuator was adjusted too low so it didn't get the right signal, tried moving it and no luck.
So i tried locking it from the boot, same fault, but when locking it from the passanger seat it staid locked

What should i do next?