The trading account cannot be logged in

My M4 trading account suddenly unable to log in and the system prompts that the account is invalid. I contacted the customer service and the customer service said that someone had sent them an email asking to change the account email and trading password, and logged in to my back-end, changed my email and password, and loss the balance to 1.68 through trading transactions in my account, but I didn’t tell anyone my back-end password. How would others know it and how could it be possible to log in to my back-end? Since my account has money, why is it prompted that the account is invalid? Why don't verify my identity when I propose to change the transaction password? I l already left the phone so you can verify it by simply making a call. My trading account cannot log in and make transaction, and the back-end can’t log in. It can completely prove that this is a fraud platform, at least there are major problems in the management, which has caused me serious losses. Please exposure them and help me recover my balance.