[Resolved]  Exide Inva Tubular It 500 Battery — No response of the previous complaint

We bought the Exide INVA Tubular IT 500 battery on 08-04-08 from BALAJI POWER SOLUTIONS(Shop no.1, Kartik Plaza, Jinsi Nala No.1, Lashkar, Gwalior. Ph.no[protected].But after six months i checked the back up and found that at 500W(5 ceiling fans working non-stop) it only worked for 40 minutes.Is it enough?
I compliant to the dealer.He said that gravity is low and suggested me to charge the battery at high current and charged us Rs.100. But still there is no change in the back up of the battery and the condition is still the same.
The invertor we are using is LUMINOUS 750W.
Please tell me that whether i have the right to get my battery replaced in this situation and what is the duty of the dealer and your company in case of such kind of poor performance of battery?

This was the complaint which i sent earlier. But there is no response from u. Kindly reply me in this context and give the solution to my problem.