Brand new car - refusing to honour warranty

Bought a brand new Magnite from Nissan Tokai for my wife. Drives nicely. Even took out the extra warranty for an additional year. After a couple of months, the gear stick (it's automatic) was sticking and not wanting to move from park to drive. Took it in and they came back with "you spilled coke into the gear box and the sugar has crystalised and therefore it's not under warranty and you have to pay for it yourself. And it will cost more than 50k". They say that the gear lever area is not sealed and so liquid can get in there. This immediately brings the question to mind that it must be a really bad design if spilling a coke in the car can lead to the entire gearbox needing to be replaced. Also, my wife and I don't drink sugar (late onset diabetes and all that). We also don't drink from cans or plastic bottles either, so there is that. Lastly, a strange thing happened as we were getting the end of the procurement cycle. They offered us a better model than the one we had paid for, for no extra cost as they were wanting to get rid of the stock or something. We asked about it being a demo model, or being involved in accidents, but they said nothing wrong and just had a 100 or so kms on the clock, which was true. Looking back now, seems quite plausible they were getting rid of a car with an issue.

Don't buy from these guys. The warranty is worthless, even on a brand new car having taken the extension. You will be out of pocket, and *****ed over. Please heed my warning. If you want a Nissan, get it from a different branch. And good luck