Dell Inspire laptop battery default

Dell Laptop obtained via FNB devices* Bought a Dell Inspire laptop through FNB, and may I add quite an expensive and supposed-to-be very effective and decent one. Experienced battery issues which they repaired for me without questions which I was very thankful for. (obviously acknowledging that it is a Dell issue). However 6 months later I experienced the exact same issue again but because the laptop is no longer under the 2 year guarantee, they refuse to repair the same default again. Is the batteries made to only last a few months? Is it only Dell laptops sold via FNB or all Dell Laptops? Not happy!!