Why does my transistor get hot?
BC337 and BC557 are rated for 800mA and 200mA respectively... how much current does the load (the door locks) want to draw? Might be able to measure it with a handheld meter.

Assuming this is an automotive door lock, one actuator will likely draw 1A or more to function.  This means >4A is needed (as a short pulse) to lock and unlock all the doors simultaneously. This might be why these transistors burn up - they can't handle that much current. Not only that, only a short pulse is probably needed and both are never shut off. 

Try a transistor like a TIP1xx, 2N3055, 2SC6144, etc. Something beefier which won't die the first time it's used or within 10 seconds. Mount it to a heat sink, at least while experimenting, to prevent them from getting too hot. Then, consider altering the circuitry to provide a pulse to lock and unlock, not a steady current. Do things one step at a time - get the transistors working to actually lock and unlock without failing first, then figure out how to "pulse" them appropriately.

Another thing to consider, since the door actuators are likely just solenoids, is "do they have built-in freewheeling diodes?"  If they do not, then the moment current is removed, a large negative voltage spike might appear across them. If the door actuators are instead motorized mechanisms, then this might be slightly less of an issue, but still something to be concerned about. Transistors have a voltage limit, and if exceeded, they will short-out and die.  Research freewheeling diodes and try to determine if you need these. Should be able to tell from a multimeter if this is happening by the voltage reading negative right after current is interrupted.