Discovery Owners Club

I have a 2012 Discovery 4 and the government car checker says it is exempt from CAZ charges, even in Class 4 areas such as Bristol. Further investigation has led me to discover that my vehicle is listed with the DVLA as an 'early adopter' (of the euro 6 standard of emissions).However, I cannot get Transport for London to acknowledge this status and exempt my vehicle in London. Jaguar/Land Rover will only provide the Certificate of Conformity (whichTfL has duly ignored as proof) and the DVLA won't provide any evidence either. The V5 only shows the Euro 5 status of the vehicle, nothing else. I don't see why TfL feels at liberty to ignore the government car checker, which superseded its own checker and is obviously more accurate, as it is linked to the DVLA. I have used stages 1 and 2 of TfL's complaints procedure, but have received no response to date. I need help from other vehicle owners who could benefit from this exemption, as I am not getting anywhere fast. Any advice appreciated. Thanks.