I've recently removed mine on a 520, don't know if it will be the same - but after removing the 3 screws move the lock and actuator down, and remove by turning the whole block to the right (whilst attmepting to get the device out of the car), I did this by getting the connector/actuator out first and then the lock body just followed on.
I had same problem removing mine - I think it looks trickier than it actually is, keep trying buddy...