How do you make money on Amazon Relay?

I know a few lads doing Amazon through Platinum.
They were getting a guaranteed £500/shift which was ok. When the diesel price fell, they dropped it to £480/shift.
A few weeks ago,they dropped the rate to £350/shift plus 54 ppm based on your weekly average over the previous 10 weeks.
To use an example, my mates average was 1004 miles/week so he was looking at a weekly guarantee of 5 x £350 + £542.16,giving him a gross of £2292.16.
If a load gets cancelled(which does happen), no mileage is paid.
So,from the initial £2500 that he was getting,he’s now in receipt of £207.84 less for doing the same work.
There’s still profit in it, but very little.