I have a transaction stuck with them for two days, nearly at the last positions of preference of mempools on most miner nodes. I kindly sent them a support ticket to ask for either a doublespend so they could increase the fee and have my transaction actually arrive, but they outright refused saying their platform isn't built for that.
Obviously, this is why you are really angry.
since you have enough experience to discover all these weak points in YoMix mixer. Why did you use the mixer? Why didn't you discover all these flaws before using the service? If your transaction had not been stuck for two days, would you have written this topic?
Of course, you have the right to demand a solution to your problem and demand compensation if you do not receive your transaction, but it is appropriate for you to attack the service and distort their reputation just because your transaction is stuck.