The way card transactions are handled has been described in Revolut’s Terms and Conditions- a separate document to FAQ.
I deeply trust you still are able to google it up yourself.
With just a little hope for further fact-based discussion, I also truly believe it is possible to understand that what happened here was the merchant’s (place where you actually made a purchase) action.
Merchant did not properly settle your transactions and so the pre-authorization charge from Dec/22 timed out, according to Mastercard/Visa regulations (7 days).
Later, having caught their error/miss, merchant re-initiated these transactions again on Jan/01 and sent out a separate/new charge that was no longer related to your initial pre-authorization charges. It couldn’t have been related anymore, because of the timeout elapsed.
With that, the new exchange rate has been applied as these were technically new transactions initiated by the merchant.
This kind of worked similarly to a hotel charging you for the room mini-bar use a couple days after you’d left. Technically a new/separate charge, though “formally” related to the initial one. Or airline purchases, charging your card without authorization at all, at any time after the purchase. Happens a lot with Lufthansa, for example.
You would see your charge only after a week, or two, or a month with no initial authorization at all.
Does this make sense?
This is really all I can help with. This is the way it has been implemented in all payment card systems across the world.
This is the way it works. And as you can see, all the possible functionalities of card payments, including reverting / re-charging / CNP / fallback type of transactions is no trivial stuff so it is not feasible to include all of that in FAQ.
Now, honestly, please. Do you believe there still is a room to escalate?
Side note- I am not professionally related to Revolut in any way and I’m an ordinary user on this community forum.