“What I’d like you to know is I went to Westminster a couple of weeks back and saw the new minister,” she said. “And trust me, nothing has changed.”
In response to her comments, ministers said they were working “tirelessly” on the compensation schemes for those affected.
As boos rose from the celebrity crowd - aimed at those she was referring to in power - she added: “It’s true, and almost all of these people behind me haven’t been paid yet.”
Mrs Hamilton said more than 300 of the 555 workers who won a landmark civil case against the Post Office in 2019 had still not yet received full compensation, including campaign leader Sir Alan Bates. She added: “They’ve offered him 30% of his claim.”
Sir Alan rejected the latest offer in May, saying the situation was “frustrating for myself, frustrating for everyone”.
The compensation scheme Mrs Hamilton referred to was launched by the previous Conservative government and offers a fixed payment of £75,000 - although many victims have turned that down and pushed for more.
As of 30 August, £87m has been paid under the scheme, including interim payments. On 9 September, Labour announced a new scheme which has a target of making an offer to 90% of sub-postmasters who have submitted a full claim within 40 days.
Mr Bates was not at Wednesday’s award ceremony. He married his partner Suzanne on Sir Richard Branson’s private island in the Caribbean last month.
Mrs Hamilton told the ceremony: “He has a plan, so when he comes back to the nation for help, please be there to support him.”
Mrs Hamilton recently met Post Office Minister Gareth Thomas.
A Department of Business and Trade spokesman said: “We recognise the immeasurable suffering postmasters have endured and that they have waited too long to receive redress.
“That’s why we are working tirelessly across government to bring them some relief with full, fair and swift redress.”
Speaking on Thursday, the Prime Minister also said the government will compensate the victims of the Post Office scandal “just as quickly as we can”.
Asked about Mrs Hamilton’s remarks, Sir Keir said he would keep to his commitment to pay the victims’ compensation.
But he added: “Almost everywhere we look there’s a bigger problem than we anticipated.
“Everything, pretty well, has been broken by the last government. We are getting on with this as quickly as we can.
“But I did make that commitment and I will stick by that commitment. We will get on with this just as quickly as we can.”
Toby Jones’s portrayal of Sir Alan earned him the National Television Award for best drama performance.
He said: “We’re still waiting for the government to make a commitment to pay the compensation before the end of the year.
“I’m sure one of the reasons that the show had been so popular is because there’s popular will that that should happen sooner rather than later.”
The ITV drama led to a public outcry about the treatment of hundreds of workers who were wrongly convicted and accused of theft, fraud and false accounting because of a faulty Post Office accounting system.
According to government figures, 253 compensation offers have been made to the 555-strong group, 207 of which have been accepted.
The government spokesman said more than £289m had so far been paid to more than 2,800 people across four compensation schemes that are in place. Most of those were not convicted or part of the group court action.
On Monday, the government also announced a new independent appeals process for those who were not convicted but handed over their own money to make up shortfalls caused by the Horizon system.