After almost 9 years of Land Rover ownership, I have come to the conclusion that the Varta / non-AGM batteries installed in these cars are of very questionable quality. They seem engineered to fail a split second after your warranty is up, but they often don't make it if you put a lot of miles on your car and/or regularly drive in hot climates. The battery on my 2013 failed about 6 months ago at 30K miles. That was despite me installing a Traxide dual battery with a capable Optima Yellowtop as auxiliary, the main one simply stopped taking a charge. The OEM battery installed on my 2006 Sport - same exact cell from what I could tell - suffered a similar fate about 18 months into ownership, with just over 50K miles (I drive 30-35K miles per year.)
One problem in my opinion is that the battery is too small for the load demanded by this vehicle. Land Rover fits a size H7 at the factory, but they could easily fit a H8 on that tray, yielding some much needed extra juice. If you are going to replace battery on your dime, I'd look for a good quality AGM battery in group size 49/H8 over the stock flooded size 94R/H7. It will be about 1.5" longer and maybe 10-15 lbs heavier, but otherwise identical and will provide the extra CCA, reserve capacity and fast recharge that the standard battery lacks, for just a few dollars more. And, you will minimize the chances of an acid spill with an AGM, which can spell disaster on a car such as the LR4 where the battery is surrounded by a bunch of expensive electrical and electronic modules.
Also, don't forget Land Rover recommends you reset the BMS - Battery Mgmt System - module (via compatible diagnostics) when installing a new battery in the LR4. If they neglected to run that routine upon replacing your original battery, that may be part of the problem. In a worst case scenario, the BMS may be feeding the wrong data about your new battery to the ECM (thinking it's still dealing with your older, failing unit), causing the alternator to overcharge it with related premature wear. BMS is becoming standard technology on many newer cars, not just Land Rover, a necessary evil of today's highly sophisticated and sensitive electronic components and systems controlling just about everything in the car, which require plenty of smooth flowing power to initialize and operate properly. When in doubt, BMS may actually prevent the engine from cranking, even though your battery may be OK.
PS: I can't speak for the 2014s, as those vehicles come with Intelligent Stop/Start technology and, I assume, beefier batteries as a result.