Vespa — hydraulic cylinder

Dear sir i am a vespa coustermer from last 3 years i own a vespa slx 150 the problem i faces is with my front brake hydraulic cylinder it has been known to me that if there is any leakage in the cylinder then the whole unit is to be replaced but sir as per my knowledge every bike comes with a kit which can be replaced inside the cylinder but as i visited the nearby dealers they said u need to buy a new one and also it's not in stock and they gave me a waiting period of 1 month. Please get a solution for this