Apply for withdrawals on January 19 but someone used my account and placed an order on January 20, maing my positions wiped out. I continued contacting the customer service but no one replied

I withdrew money on 19/1/2021 But on 20/1/2021, someone used my account to place an order, which caused the money in my account to burst. I kept contacting customer service and there was no reply. Please give me an explanation