Sukam — backup problem

I am having 7.5 KW sukam inverter and 5000 W sukam's solar panel with charge controller. From june 2014 i am facing backup problem, after launching many complaints i got the service for which i was charged 8500 rs, though the engineer assured that it has been fixed but it was not so. Again when i launched complaint the engineer came and asked me to change the battery, i did that but no improvement was seen. I have launched many complaints-24/05/2015-[protected] 05/06/2015-[protected] 10/06/2015-[protected] 19/06/2015-[protected] and many more complaints before, those records are deleted from my phone.after launching complaints i get the service and those engineers assure me that the problem has been solved but it arises again.I have a good battery but even i am unable to get backup. so i request you to go through this and try to fix this as early as possible by providing a good service with a good engineer. AJAY KUMAR LAL PETROLPUMP DEALER LAL BROTHERS, FAIZABAD ROAD, AKBARPUR, AMBEDKARNAGAR. U.P. email id-a.[protected]@gmail.com Mobile No.-[protected]