[Resolved]  Amaron Fresh Battery — Battery gravity decreasing

I purchased an amaron fresh 12V/150 Ah battery for my Sukam inverter on 14/12/2007. One month after the backup time decreased. When I contacted the local dealer, He took the battery to the District dealer for replacement. The technician of the district dealer told that there is no problem in the battery. The gravity was down because there is a problem in the inverter. He increased the gravity and returned back the battery.
I took the inverter at the service centre and got it checked and found that the inverter is perfectly ok. I again contacted the dealer technician but he was not ready to accept the fact. He told me to check the inverter from another service engineer. I did the same by taking the inverter in the another city. Again, I found the inverter working fine.
The dealer is not ready to replace the battery and only harrassing me.

Please do the needful.