Translation:Our elevator is out of order.
There is 升降机 shēngjiàngjī but I never heard anybody actually use that word. When I hear 电梯 my first interpretation is an elevator, not an escalator (although you're right, 电梯 can refer to those too). To unambiguously refer to escalators there seem to be a couple of words. I would say 手扶梯 but that may be a Taiwanism. Apparently 自动(楼)梯、自动扶梯 and 电动楼梯 are also in used in other places.