Used Car Warranty issues

Hello

i recently bought a used Mercedes E Class from a garage with a 3 month warranty on it. The air-suspension system has a fault on it whereby it drops the rear of the car down fully about 80% of the time that I park it up. It means that I must wait to pump up the car for about a minute before driving away each time. My garage is resisting covering this under warranty and I feel strongly that it is an issue that is covered under the details laid out in the warranty.

Has anyone had any similar experiences or advise they could offer?

Thanks in advance

Brian