If I pay a subscription, there should be some customer support

Well, the CS folks can’t make changes to the game to grant you the progress. If it is bugged sometimes they don’t even know about it - hence check the forums and if it IS bugged, put in a Bug Report so they can investigate and patch it.

However, there IS a Forum Support Agent comment on that over in Customer Support. It won’t resolve anything, but at least you can see the current status of the discussion.

https://us.forums.blizzard.com/en/wow/t/vicious-saddle-bug/829300