I want to stress one specific fact, which clearly separates honest and dishonest behavior:
If an additional clearing followed by margin calls happened WITHOUT spot market movement into the same direction (or even worse, into different direction), then it's clearly an abuse.
If the spot market moves and additional clearing is done to adapt to changed conditions (and direction of futures price change corresponds to the spot market price change), then there is no dishonest behavior involved.
I would disagree with this point, but note that I used the word deceptive and not dishonest. Though I do believe that you have something to gain by doing a manual clearing in that the exchange has reduced risk (this should not be disregarded, as risk is used as a financial instrument), my main point is that the trading range on the site and the definition of a trading session led many users to believe that they would at least have some time to react to >10% market moves.
It was grossly negligent on your part to implement this risk management solution without redefining a trading session and giving everyone with a contract notice and opportunity to object. Honestly, I still don't believe you should be able to do so without everyone's permission that is still in a contract with you. A trading session should not be defined outside the contract to begin with. This is a material part of the contract that was (and still is) omitted.
While I believe that negligence caused the entire loss that I endured, I don't think it would be realistic to hold you accountable for the entire realized loss for the contracts. I'm actually not sure what would be fair in this case, and I'm open to suggestions from the community, but at the very least the fees should be returned or credited towards future volume.