Got a response from Sixt for anyone who was curious of the outcome. Here is the reason for no miles!

Dear Mr Vidrine,

Thank you for your e-mail and please accept my apologies for the delay in response.

I understand that you have been querying why your Air Miles points cannot be linked to your recent rental from Sixt Luxury in Bayswater. Unfortunately Sixt Luxury are not linked to this reward scheme and you can only claim them if you book through Sixt direct. I appreciate this is very frustrating as your rental was of a high amount but as Sixt Luxury is a franchise of Sixt, we cannot link these together. Sixt Luxury are currently in the process of putting measures in place to offer this, however this is not complete at this time. Therefore we apologise if there was any confusion caused at the time of collection at the branch.

We would like to offer you an upgrade voucher for use on a future hire with Sixt as a goodwill gesture for your recent experiences. The voucher can be used up to 12 months from the date of issue and can be redeemed at all Sixt branches in Germany, Austria, France, Belgium, Switzerland and the Netherlands. In addition it can be used in the UK, Spain, and our USA locations.

If you would like to accept the voucher, please respond as soon as possible with your full name and postal address.

I am sorry that I am unable to reply more in accordance to your wishes on this occasion and I look forward to your response.

Best regards