Cannot close the position

I bought rise for 0.5 lots and the "forbid operation" pops up after pressed close the position. It was the only button for closing the position. After I pressed the button and the "forbid operation" pops up for many times, it changes to 6.6 lots from 0.5 lots. Then, it rose sharply and dropped sharply and my position was wipe out. I asked customer service, the customer service said that there is nothing wrong with my account and it might be the operation error casued by the lag of the internet, but I was operated at the best internet of my home. So, what do you think about this situation. Is it a fraud plaform?