Why can't I access my USD funds

I have been trying to send money from my USD account to NGN account but I keep getting rate not available for this currency. I have lost businesses because I can't send funds. When I contacted Africhange customer support about the issue they promised it would be resolved in 24 hours. This is over a week and I'm yet to get a response from Africhange and also not able to access my funds.

This is frustrating