After more than 1 year I finally knew the downside of this broker. My profit for GBP/USD was canceled because of rule violation. Below is their email:

Dear Xxx,

We hereby inform you that Control and Security Department has performed a correction on your account with the following parameters:

235.56 || CANCEL ERROR ORDERS

On your account xxxxx were fixed orders contradicting with point 3.14.6. of the Public Offer Agreement:

3.14.6. The Customer agrees to undergo a supplementary expert examination of the trading account, if it has been revealed that the trading methods of the Customer include opening and closing/opening lock positions with a less than 5-minute interval between them. In accord to the results of the supplementary examination the Company reserves the right to correct the outcome of the Customer's trading by the sum total of such orders.

We apologize for the inconvenience, and feel free to contact us by email address antifraud@mail.instaforex.com in case you have any questions.

This is so disappointing. I don't want to ruin their reputation so I can only warn for traders to be really careful if they intent to trade with Insta.