Land Rover DPF issues

My car has been with my dealer for nearly 4 weeks waiting for Land Rover to authorise a warranty replacement of the DP Filter following an amber warning followed within 2 miles of a red Filter full warning.

Land Rover assist were called late afternoon and arrived close to 5.00pm .Checks carried out showed that the filter was at a level that could be regenerated by the technician. However as it was late in his shift, he was not able to do so as it was time to go home. He advised it would be ok to drive 4 miles home and his colleague would attend first thing the following day. The second technician ran some tests and found the filter now to blocked to carry out a re-gen and the car would need to be transported to the dealer where it still sits.

I was advised by the dealer that the filter would need to be replaced and it would be very expensive, Land Rover were asked to cover the cost of replacement but after three weeks of claiming that no case had been raised, they declined claiming that the cause was the driving style and that diesel cars are purchased by people intending to drive at 70mph for long periods.

I have had the car for 2 years without an issue, so doubt very much if the driving style is the issue or it would have surfaced earlier.

I would be very interested to hear specifically from and member who has had similar experience with a Land Rover. I am looking for supporting evidence that Land Rover are using this excuse to avoid warranty claims, as there appears to be some accounts online.

Very grateful for only Land Rover related replies in this case.