The First Group review: They took me 30,000$ as hospitality fees after cancellation of transaction

I came to Dubai as an investing guest of the first group. I wanted to bye one unit only but they persuaded me to bye 3 units and paid 30,000$ instead of 10,000$.
2 days later I wanted to cancel the whole deal and get my money back. I went again to Dubai un a "free" trip they give to every investor. I agreed that they keep 10,000$ to cover the hospitality trip and pay me back 20,000$.
I didn't get any money return and they don't reply to my messages any more.
what can I do to get my money back?