I wouldn't call that scamming. Their margin trading facility is not intended to deliberately cheat on customers; it's simply a "quick and dirty" hack, with all the bugs and shortcomings that belong to it. Simply don't use it.
well yes, I agree, I just realized I might even have come out ahead if you include past trades... still pretty ridiculous though that they don't even tell you about the problem or aknowledge it.
Imagine you wanted to use this to hedge a large trade for example... What a huge mess!