Is joining tenant association important?

Hello guys,

I'm living in berlin for more than a year, and I find dealing with landlord is challenging, my last landlord cut around 400EUR from my deposit and the current one is not really helpful in terms of maintenance, he started responding when I sent a series email with legal info.

My question, would joining https://www.berliner-mieterverein.de/sprachen/englisch.htm help in such cases?

Is it worthy?

Thanks