I’m sorry you’ve not yet had a reply, Cyril. I know the team is always very busy around the time of Musikmesse because it’s the support team who are talking to customers all day every day in Frankfurt, and as such the support team in Hamburg are short-staffed, and a backlog can build up.
If you were accepted for the crossgrade back in November, there’s no reason why you should not be accepted again now. The approval you received in November was valid for 30 days, so you will need to submit your proof of eligibility again, but you can simply re-submit the proof you supplied back in November, and you should find that you quickly receive confirmation that you can complete your purchase.