Hi Gaiuslulius,
I am not from Laminar Research; just a flight simmer from down under.
Like you I have a XP11 disc version.
There are two legal versions of X-Plane. One is direct from Laminar Research and clearly marked on the packaging and the other is licensed by Laminar Research for Aerosoft to sell in the South Pacific area and in Europe. I presume you have an Aerosoft version as you purchased through Amazon.
This forum is not the place to solve your problem. But, I offer the following advice. You will need to provide proof of purchase (receipt copy) or at least a photograph of the boxing. Replacement discs have previously been made available for XP9 and XP10 so I expect that XP11 discs will be available also at a small cost.
If your version is marked on the packaging as Aerosoft then you should make contact direct with Aerosoft. I don't have contact details. Failing that you could make contact direct with Laminar Research starting at [email protected] There is a more direct contact for a replacement disc with Laminar but I cannot find the details at present.
Good luck
Glenn