First of all, if its hard to contact your account manager, maybe it's a time to change a broker.
Well, basically you are saying that your broker is denying your withdrawal request due to an existing open trade?
Then, close it by using the same method you open the trade. Is it by phone? or using a platform (like a MetaTrader or web trader), but
If your request still been denied after all the trade has been closed, then you should really need to re-read their term and conditions.
How did you opened these trades?
If you did it through a MT platform or your mobile, go there again and close the trades.
If you did it through your broker, then contact them.