1 - National tyre chains are generally staffed by surly minimum wage teenagers, and the thick kid from your school days who liked to eat crayons is probably the assistant manager. They are "experts" at fitting tyres to wheel rims and nothing more. It is utterly unreasonable to expect them to have an encyclopedic knowledge of every make, model and variant on the roads.
2 - You are not going to find the information you want from Landrover. As mentioned by someone else earlier, you can find a balance of proof in your favour from various aftermarket freelander garages, which will go some way to helping. However, this is a moot point because.....
3 - A year ago? As soon as this occured, you should have sought proper legal advice*, who would probably have told you to have the vehicle inspected by an independant vehicle engineer.
4 - Looking at this from the garages point of view, you knew and had proof that the tyres were the wrong way round, yet you continued to drive the car. That did you no favours.
*Proper legal advice - a lawyer, preferably one experienced in such matters. this would probably have cost you money, but would have been a good investment.
When my teeth hurt, I see a dentist. When my roof leaks, I speak to a builder. When I need legal advice, I speak to a lawyer who knows the facts. Its a simple philosophy that means that when I encounter situations in life that I cant deal with myself, I am guaranteed to get accurate, relevant, timely information rather than a bunch of ramblings from strangers on the internet.
