It is not about being fair or unfair. You need to read the Terms and Conditions of the gambling website you choose to bet on. For retirements in tennis, different books apply different rules. Some pay out for the win, whilst others void and cancel bets if a retirement occurs. In this case, Cloudbet voided the bet, which is part of their rules. Sometimes it goes in your favour and other times it doesn't, but rules are rules.
Where did you find this rule? I looked at cloudbet's sportsbook rule for tennis and it says that all bets will be only voided once a player retires before finishing the 1st set. I'll quote everything.
Tennis
One full set must be completed for money line wagers to stand. If less than 1 set is completed, all money line wagers will be void. The winner of the match is the participant declared the victor by the umpire of the match.
If a player retires before the 1st set is completed, all wagers on the match will be considered void.
@Chevas.Regal Your bet is definitely settled wrong here go visit the site and click the question mark logo on the bottom right then submit a ticket to their support so they could regrade your bet to a winner.
@ralle14 , they replied me in email and said that it was a cancel bet according to their rule
what should i do now. Should i move to scam accusation?
"Hi Chevas Regal,
Thank you for contacting us.
According to our rules for live tennis betting, if a player retires all undecided markets are considered void. That is why your bet was cancelled and your stake was refunded back to you.
You can find more details about our tennis sportsbook rules on the link below:
https://www.cloudbet.com/en/sportsbook_rules#live-sports:tennisI hope this helps clarify your query, but if there's anything else I can help you with please let me know.
Best regards,
Mark
Cloudbet Support Team"