It is a genuine Vx, and it's done 4 years. Not a short life for a car battery but not long either.
sadly it makes no difference how old or who made it
I've had cheap batteries last years (ones that where on cars when I brought them) and an expensive battery fail under warranty .
winter is coming ,£50 spent now on a battery could actually save you money and hassle in the long run
trying to start a car with complex electronics with a duff battery can damage expensive chunks of electrickary
windings in the fuel pump, starter motor and solenoid heat up if voltage is too low to spin it up ,relays chatter ,ECUs shut down or worse, none of the many engine sensors read true values at low voltage
it's also important to make sure earth points and battery terminals are clean and sound too ,for the above reasons.
yes, I am a Builder, but I trained as an engineer in my early days ,so i'm not trying to make you spend money part swapping and i'm not on commission from battery suppliers
get someone to crank it over while you read the voltage at the battery when doing so
the sub £15 lidl aldi battery chargers do a conditioning charge using PWM i think
I have an ebay charger that does the same, I keep spare batteries charged and swap rather than trying to jump start with leads if a battery is low,
so you could also consider getting a charger,keeping the old battery charged up as a stand by ,for when you leave the sidelights on
sods law section 3 ,item f7 ...." if you have a spare something,the one fitted rarely fails "