They dont enter yard even when gate is not locked

My alarm went off on Tuesday (9 Feb 2015) at around 7PM and i was not home . they just left a note that the wall is too high even though the gate was not locked. my concern is what if i was inside the house and i was being attacked . where they just gonna turn arround at the gate even though it was not locked. this is the second time i am complaining about this issue this year. if things do not change i would have to change service providers. I logged a complain in Jan 2015 and they called me promising that things will change. I pay a lot of money for what ?