£60.00 a day is a pi$$ take to be honest nowadays, you get more packing sandwiches, with guaranteed dry working conditions, paid holiday, paid sick, the guy you're working for doesn't try to rip you off to be sure he's earning 10 times what you are; anyone working self-employed for £60.00 a day is a fool to themselves IMO, no wonder they wanted more !
Pay peanuts, get monkeys.
When I first started the guy who ran the business paid those who worked for him 75% of the amount they'd done. Seemed fair, they were after all doing the work, he had to do very little for his 25%, I would have thought you'd ahve known that.
15%? I seriously hope you are having a laugh.
Matt