It happened to me last week with Pepperstone , Australia account. The Copper prices were frozen for three hours in London session. There was no tick data appearing. I constantly contacted support. They said that no data coming from the liquidity provider . I can see the live prices on other online platforms but cant do anything .I had stop loss for a short position. When after three hours, the tick data resumed ,it opened at the higher price than my stoploss and trade was stopped at the first tick price rather than my stoploss. It was frustrating to see the PA somewhere. I could not able to help!! I am still figuring out how to accommodate these risks in my trading plan. Please let me know if you have experienced similar situation.