Consumer Redressal

I brought a HITACHI Split AC(1.0TR HITACHI KAMPA - RAU312HUDD) on 25/05/2014. two company service person had come to install it. but from the day of installation there was water dropping from indoor unit.after complaining several times they fixed the problem temporarily.this happened more than three times.Now just warranty has expired on 25/05/2015 and the problem has started again. I have lodged a complain(15052501893) on 27/05/2015.but now they are claiming that there was problem in alignment at the time of installation and demanding full service charge now. they gave me a contact no(9674410460) to solve this. but after hearing the problem they are not receiving my call any further what should i do to resolve this?