LOTTO ticketholders with five numbers in Wednesday's draw were left frustrated after they won less money than those who matched only three.
Camelot said more than 4,000 players matched five of the six balls to win £15 each.
Echo reader Michael Smith, from Benfleet, was one of those affected.
He said: "Yippee, I thought. I got five numbers on the lottery, just think newer car or holiday, I was so excited.
"I checked the numbers and to see how much I was in for. Three numbers paid £25, four numbers paid £51 and there it was, with its disappointment fivemnumbers paid, £15.
"I felt cheated, so that's it for me and the lottery, as the system in my opinion is unfair and needs looking into. Have any other readers had this experience?"
Those 4,000 players won £15 but 7,879 ticketholders with four who won £51, while the 114,232 people who matched just three balls won £25.
No one scooped Wednesday's Lotto jackpot, sending Saturday's prize to an estimated £28.2 million.
The winning Lotto numbers were 14, 21, 42, 35, 07, 41 and the bonus number was 43
A Camelot spokeswoman said: "We had an unprecedented 4,082 Match 5 winners last night.
"This is because five of the six main numbers drawn were multiples of seven - 07, 14, 21, 35 and 42 - and clearly this is a hugely popular set of numbers.
"To put it into context, the four Lotto draws before this one had 55, 36, 61 and 38 Match 5 winners - so over 4,000 Match 5 winners is extraordinarily high.
"It is a lottery at the end of the day, and the prizes people win are down to the balls drawn and the number of people who match with those numbers. As a result, we do sometimes see extremely rare situations like this."