Does my broker has the right to reduce my leverage suddenly without prior notification?
If “Yes” on what conditions?
If “No” how can I seek redress if it happens and close my trades at lost positions?
I’m not sure about prior notification but they can definitely lower your leverage at any time they see fit. Normally around really volatile times such as news events (Brexit), world events (Covid-19 outbreak) or even the behavior of the currency (recent devaluation of the Turkish Lira). If they see the pick up in volatility is something on going then they start lowering leverage.
The leverage entirely depends on the broker so if they have reduced it suddenly, it is better that you ask them. Something like this seems to happen during high volatility periods. I have been trading with Ig and Fxview for some time and so far I haven’t faced this issue. But whenever I do have a query, I just contact them. The customer support is quite efficient and there’s no wastage of time.
You should ask them why, and what right they have. Then tell them to show you where it is written in their terms and condition that they can reduce the leverage at will. Once they show you, and you feel like moving to another broker. when you get there, make sure you read their TOS on this matter. Some brokers are very clear on these issues.