Eric Walker, 56, has been locked in a bitter dispute with Camelot after claiming he'd won the jackpot on a Â£3 Pharaoh's Fortune scratchcard.
But the firm has said the won't be paying out on the card, bought at a local corner shop in Arbourthorne, after its said that letters on the card had been altered.
Camelot refuted Mr Walker's claim that the altered card was a result of a misprint after launching an investigation into the issue.
A spokesmanÂ said: "Based on the photo we were sent we were able to reconstruct the scratchcard in our system.
"We can confirm that an F has been altered to appear as an E and is therefore not a winning Scratchcard."
Yesterday we revealed how Mr Walker, a dad-of-four and who buys six scratchcardsÂ a day hadÂ claimed the big-money win after matching three symbols on the card.
But lottery organisers Camelot refused to pay up saying that a letter F had been altered to look like an E.
Mr Walker said it was the result of a misprint and insisted: "I'm no cheat."
He added:Â 'I've matched the three symbols like the card says and I've won. They are saying it's not a winner and we've cheated.
'I'm not prepared to let this go. We're being swindled out of Â£200,000 by Camelot.'
Mr Walker says the money would be "life-changing" for him and his partnerÂ Amanda Emmadi, 37
The game offers five top prizes of Â£200,000 by giving sixteen co-ordinates which are used to scratch off squares on a grid in the hope of matching three pharaoh symbols.
Mr Walker,Â who has children aged between 14 months and nine-years-old, said the money would beÂ "life-changing" for him and his partner.
He added: "In my eyes, I've won Â£200,000 and I'm being cheated out of the money.
"They're trying to tell me that an F has been changed to an E but I bought the ticket and scratched it myself."
He added: "I haven't doctored it, I'm not trying to cheat.
"If it's a misprint then that's their fault and they should still pay out, it's nothing to do with me.
"I'm going to keep the pressure on Camelot to sort this out, I'm not willing to let it go."
'They want to inspect the ticket but I'm not letting it out of my sight. It's a winner and I'm hanging onto it.'