Keith Smith
As a tradesman myself I always take a 50% deposit before I start work, this balances the risk on both sides in that the customer has to trust that I do the work and I have to trust that they will pay the final 50% on completion. This seems perfectly reasonable to me and I have never had any objections from customers old or new.
As for the drive, i would investigate hiring a vibrating roller and seeing if you could compact the hardcore down further. Then apply as much MOT as will fit and roll it down, again with the vibrating roller. This would be a lot less work and infinitely cheaper than trying to dig out the hardcore and may well work better than just MOT whacked down with a plate vibrator.
As for the drive, i would investigate hiring a vibrating roller and seeing if you could compact the hardcore down further. Then apply as much MOT as will fit and roll it down, again with the vibrating roller. This would be a lot less work and infinitely cheaper than trying to dig out the hardcore and may well work better than just MOT whacked down with a plate vibrator.