That's a good action from your side. since UnioChange does their business but their management handles customers unprofessionally. Removing them from Bestchange.com is not going to help OP since the accusation running and you cannot avoid your liability just by removing UnioChange from BestChange.com. We expect you should talk with both Customer and UnioChange and solve this if possible.
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We expecting a solution from BestChange.
How exactly do you expect BestChange to solve this? Get money from their own pocket and pay up the victim due to some careless error due to the two parties?
I mean, they are not the ones who "scammed" the victim. It's a case between the victim and Uniochange.
Getting them delisted as investigations go on is the best thing BestChange can do at the moment.