Ernest
Stupid IDIOT
There was a guy a few years ago did an acca online and by the time the last horse ran he had already breached the pay out limit, so the last horse ran knowing he wouldn't win anymore but could lose the lot which it did.
I'm no expert but if you knew at the time of placing the bet that the winnings would exceed the payout limit could you not place several smaller bets with the same online company?
On Betfair multiples if the payout (at projected BFSP) exceeds £1M they warn you when placing your bet.