"...but if you have sent such sum by mistake, contact our help desk."

Hi! I'm planning to use Mixtum.io since I've heard a lot of good feedbacks from their previous users or i must say clients, also no questions ask on the Premium anonymization they're offering (that hopefully worth the price) i just a one concern, as  a person who usually commit errors, like who doesn't, right? my question is, How fast or how long is it taking them to respond to human errors concern and let's say technical concerns in general. how do they usually respond do they have live chat or via email and how can they authenticate the client if they don't store information and/or customer info.? i would appreciate a response. Thank you!