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.