After contacting liquidators, Ms Roberts was told the vouchers were irredeemable and it was not possible for refunds to be issued.
Her request to use them at another of Mr Purnell's restaurants was also rejected.
"I'm really disappointed," the 58-year-old said. "He classes himself as the 'Yummy Brummie'. He blames greedy chains taking his business but he didn't want to communicate or come to a compromise with me.
"I thought he was a better man than that. It's left a rotten taste in my mouth."
Ms Roberts previously visited Purnell's with her husband, describing it as a "great experience".
She said she really enjoyed dining at the premium establishment and wanted her loved ones to be able to try it too.
"He's come across as a down to earth boy from Chelmsley Wood," the mother added of Mr Purnell.
"I thought he would understand what it was like to be an ordinary person in the street."
Ms Roberts was among multiple customers who were told to contact their banks to try and secure a refund, but many received them as gifts and in some cases up to a year ago.
Sean Devlin, 72, from Malvern, Worcestershire, said he held a £110 five course lunch for two ticket, which he can no longer use.
The retired head teacher received the voucher as a Christmas gift last year, but was told Purnell's was closed when he tried to book a table.
"I have had no information at all from them," he said. "It makes me cross really.
"They have had a difficult time, but so have many other people. I'm sure they have made good money over the years."
Angela Blacker, from Broseley in Shropshire, received the same voucher as Mr Devlin, as a present for her 60th birthday.
The retiree was surprised when she discovered the gift would not be honoured.
"I'm shocked at the level of customer service," she said. "We have had absolutely nothing at all.
"It's not our fault he's closed the restaurant. I was really looking forward to going somewhere posh, but it's not going to happen now."
