SD Vehicles

Bought a 2017 BMW X5 M50d from SD vehicles in February, it looked good at the time so I went ahead. So he gave me 3 months warranty with some auto group company with only a claim limit of £2,500. Anyways the V5c was delayed because SD vehicles told me they binned it for some odd reason and I have to apply for a new one myself. which made meant I was getting tickets on the X5 every few days so he covered the cost of the tickets only because he chose to bin the V5c. A month later I noticed the brakes were squeaking so I asked him if he would cover the cost of the pads and I will cover the brake discs cost, he refused and said he would only do one side pads only. So I said thats fine and he covered the rears. Now I noticed a judder and immediately worried that its gearbox related, anyways had it inspected and was told its a leak on the transfer box which is bad news, I saw myself so 100% I can confirm the leak. Went back to SD vehicles as it hasn't been that long since I have had the vehicle and it’s a little outrageous to have this issue so soon. Now his refusing to cover the cost as the 3 month warranty has run out, But why was the warranty only 3 months? Why not standard 6 months. Anyways I would say be careful when buying vehicles from this place as he wont look after you if there are any major problems with the car, basically your on your own. If I was a business owner I would always look after my customers, but I don't think thats important to him. Now I am having to paying £4000.