I think I’ve been scammed by NetForexTrading. What should I do to get my money back?

I was approached by a so-called "investment expert" online,National regular foreign exchange trading platforms who introduced me to NetForexTrading. They guided me through setting up my account, and initially, things seemed fine. I made a $2,000 profit and even withdrew it without any issues. But then I decided to invest more, around $15,000. My account showed a profit of $10,000, so I had $25,000 in total. But when I tried to withdraw, they claimed I needed to pay an additional $5,000 for a "maintenance fee" before I could access my funds. Now I’m really starting to wonder if this is a scam. Has anyone else faced this with NetForexTrading?