Hi Soohia, I will cut a long story short. Based on the MT4 server capabilities, your order was likely slipped. So if you set a TP you had a hidden spread markup, this would have led to your ask and bid getting wider for a few milliseconds enough for you to be exited at what you call the wrong price.
This is common practice, especially if you are trader that consistently losses and uses stop losses the broker will chase as many stops as possible. I think you have to evolve, time has moved on. You should no longer be doing what people tell you, your risk is your own. In the end, stops and other risk measures will not work in desperate situations anyway.
Here is the point were you realise no one here can help you, it is your job to find a broker that would not do this, it is possible you may have to downsize risk and stop using stops, you may need to even change platform from MT4, the truth is you must take more responsibility.