Generally, Wizz Air is non cooperative at all, has no tools and interest in solving issues and helping customers as soon as you've purchased their product, like in my case

Thx for a prompt answer. I did not solved the problem in a way I wanted to. Instead of repeating asking the Wizz Air team to help me with my reservation (I called and I wrote), I've changed the flights for another one (comming soon and couldn't wait too long for a potential solution from GetHuman environment) and payed extremally enormously high charge fee for rebooking (GBP ***) plus quiet high difference in tickets price but that's obvious added to previously made reservation for GBP***. Avoiding not proportional change fee when rebooking, was the reason why I wanted to purchase Wizz Flex service hoping it could minimalize the cost of rebooking (by the way, I just ignored choosing the service during making my main reservation). Had no idea it will cost me a fortune and Wizz Air is not giving an opportunity to repair mistake even in such a short period of time after reservation. So, the problem with adding Wizz Flex service after stays like it was. Even if I was trying to purchase Wizz Flex service about ** hours after reservation was made.*Eventially, I stay veerryy dissapointed and I'm not saying a single word to my wife :(. *Think Wizz Air has no proper way or is not giving eunough possibilities to repair mistakes in a short period of time after reservation. Being sure now, Wizz Air is a very expensive so called budget airlines. Thank you for an interest in my case, Valters B.