Severe slippage

My orders were closed maliciously without reaching the stop loss price. Besides, there is a slippage deliberately and there is not such slippage in other platforms. I wanna know why did this order reach at the stop loss price. There are more than once severe slippages. They were courteous to me when I deposited. The broker has been changed or vanished when I met problems. The stop loss price wasn’t reached in other platforms except this platform. Yet the price went up after reaching the stop loss price.