I commerce in commonplace crypto buying and selling.. initially I commerce for $100.. After they requested me to pay $300.. And mentioned then solely I can obtain my revenue.. after they mentioned commerce accomplished.. and I obtained revenue $4500 .. They mentioned to obtain above revenue I ought to pay sign Arriers charge $1250.. I paid sign charge additionally.. now they asking me to paid improve charge $2700.. why ought to I pay?. is it obligatory? Or I am being scammed by them?