HI Dufalu, Your profile doesn's say where you live but when I did a google search, I found the following sites in the U.S.A. that sell Rosa 'Champagne Cocktail'. One shows it as Out of Stock:
https://roguevalleyroses.com/r...
https://www.heirloomroses.com/...
I also found this U.K. site that has it listed but it's apparently also Out of Stock here as well:
https://tree2mydoor.com/produc...
You could check with nurseries and garden centers in your local area to see if perhaps they carry this particular rose or ask if they could possibly order it for you. Or you may be able to contact one of these online sites and ask to be put on a notification list for when it becomes available.