Orion E201
Attery backup found very weak

I had Purchased the orion mobile modle no E201 from home shop before one month.first week the mobile battery back up found ok.after that the battery back found very bad. After getting full charge of battery again it has required charging after using the mobile of 5 to 6 hr. Our usage of the mobile is only for calling. So pl reply us for replacement of battery at earliest