@mike4scuba: While some battery depletion is expected over time, there are steps that you can take to extend the overall battery life. Please take a look at the link below, and try out some of the suggestions to see if you notice an improvement.
How To Save Your Smartphone's Battery | Samsung UK
If you're still concerned about your battery life following the steps above, please reach out to our Help Desk on 0333 000 0333, or on Facebook or Twitter, and an advisor can arrange for the device to be inspected under warranty. The battery is covered for 12 months, but this can only be replaced at the discretion of an engineer as part of the warranty inspection process.