Many of us tries to sell dollar locally to companies like paidaz.com. But paidaz is a complete scam.
They will gain your trust in the beginning. They will send you money time to time when it is small amount.
And once you start trusting them and send them a big amount, you will never get your money back. Even they will behave rude with you.
I recommended you use Payoneer or Wise to send money in Bangladesh directly. Signup from my referral links, you will get free transfers and also bonuses.
Have a nice day.