Shame, because what Mr WULLF said (awesome name

) looked and sounded promising. Were you careful? He did mention that over adjustment would definitely make it spit the disc out!
If not then I would chance your arm with Sainsburys. I've always been aware of the six year rule, but never had the inclination (time consuming) to follow it through, mainly because the onus is on you to prove that it isn't fair wear and tear; i.e. you haven't been ejecting and re-inserting discs 200 times a day for eighteen months!
You could claim that all you've ever really done is play a digital download of BF4, so hardly ever touch the disc drive. Just for your info, John Lewis give 5 year warranties on their TVs, but only two years on built in DVD drives. They know it's an issue even if you hardly ever use the built in drive (heat perhaps?), so that could bolster your argument that 18 months is completely unacceptable.
Good luck Lieutenant! If you pull this off there's a promotion in it for you.