How can they tell you your sensors work if they have not come out and tested them. If you look at your contract it will say if your paying them to service the alarm, If your paying then get them out to do it properly for you. Why wait till a burglar tests the sensors and then find out they dont work. I know they say they can dial into your alarm to test it. I can do this myself but i cant test your sensors over the phone.
I would shop around than pay the prices you are being charged. €200 for monitoring plus a maintenance contract for the year is average but i have seen alot of places charge more.