Are you sure that the hourly rate you quoted is correct. 25 dirhams an hour puts labourers on 1,000 dirhams a week for a 40 hour week (which they would never work it is more like a 12 hour day 6 days a week, so a 72 hour week), or 4,000 dirhams a month. I think you actually mean they got a payrise from 2.50 dirhams an hour up to 2.7 dirhams an hour.
So I think you will find the increase is 2.8 UK pence per hour.
Your point is right though it is modern day slavery, and it is disgusting, but hey how much do we pay our housemaids and nannys so I guess we are all part of the problem.