I don't exactly know what you mean by "earn with arbitrage", but I do have an update to my earlier situation. I contacted profiforex customer service and they realized there was a server error and credited my account.
I am now happy with them. I have been a customer for over a year and will continue to be one. Better to be with a good unregulated broker than with a crap regulated US broker which makes you have thousands of dollars in an account to earn pennies! Dodd-Frank legislation makes US look like garbage for trading forex. No wonder why China is set to lead the world soon.