Land Rover Centurion lack of after sales

I bought a secondhand Land Rover Defender for R1.1 M from Land Rover Centurion and I expected a certian caliber of service especially if you that much for a Vehicle. I received the vehicle and then the coolant low red light came on which is serious. I took the vehicle back and was told that they had to replace the water bottle. After 2 days there was no feedback and I phoned,I was then advised that they wil not replace the bottle and all is fine I can get the vehicle. I then strugggeld to sign in with my Land Rover incontrol app. When I phoned the salesman I was told that they can resolve the problem and that was that. Up until now my 2020 Defender still can't sign in to the apps and be fully utilised as it should be. It has been more than a month and a halve