I feel for you mate. I would say forget trying to win them at Auction. You got more chance of finding an ocean in the Sahara. If you weren't able to grind them out the way PG wants, no can do. Just spent hours trying to reach 215mph on the Cotswolds speed trap. Going to bed now, had enough. The whole point of playing games is for the enjoyment, not that you feel so frustrated you feel no passion, no nothing, just a sickly sense of grinding in the hope that you MAY strike it lucky by some miracle.
All just to win one Merc. Shame they stopped DLC (excluding the Barrett Jackson pack from FM7) which doesn't count IMO because it's just regurgitated content.