There’s no gesture of good will on the part of Betfury. The gesture of good will goes to the OP for agreeing to cash out value rather than true value.
True value consists of 4 winning slips and 11 losing slips if all the matches had their outcome which did not happen.
Betfury acted on minimizing their risk [OPs betting pattern was not normal], they voided the bet. When a bet is voided the original stake should be returned. We have a case if that was not returned, but if that was returned and Betfury agrees to add anything additional then of course it's a gesture of good will from BetFury. OP should be happy about it that his original stakes are back to him. Has he got his original stakes back?
You can cancel a leg but not void the whole multi.
Rule 4.4.13
In case a Bet included in the Bet Builder Bet is voided – the remaining (non-voided) Bets included in the Bet Builder stand.
https://docs.betfury.com/betfury/terms-of-services/sports-betting-terms-and-conditionsOP- You have 6 months to file a complaint under the new LOK law in Curacao. You must use an official form.
Reporting this is worth a shot but history has shown that on occasions where a casino is ordered to pay via Curacao courts, the casino can simply deny renewing their Curacao license and move to a different license. Usually Comoros.
There have been cases where this happened. And casinos have little to lose because the Curacao license doesn't even allow operation in Curacao, they have no customers there.
So if BetFury had it in their own terms that they can't cancel a mutli bet because of one leg then they're in the wrong. But the OP must consider other factors too. If Betfury can substantiate that there's suspicion of matchfixing in these matches other casinos may have even confiscated his balance. So BetFury may be waiting for some feedback by their bookmaking partner. If the transcripts are released it could be more obvious.