Rosie Belhamza, who wears a prosthetic limb from the knee down, was trying to get special access to rides at Alton Towers.
In previous years the admin officer had simply needed her Disability Living Allowance letter.
But this year despite having this paperwork - and her obvious disability - the theme park, which claimed to have improved its service, said she needed the extra documentation.
The 47-year-old from Derby suffers from diabetic neuropathy and it led to her losing her right leg after an accident.
When she visited the theme park last year she said that all she needed was her Disability Living Allowance letter, but this year when she called the park, in Alton, Staffordshire, staff said they now needed to see a doctor's letter.
She told The Mirror: 'I'm angry. They told me to book an urgent doctor?????????s appointment but I think most GPs would find this unacceptable. Many also charge up to ?????????50 for a letter.'
In its disabled visitors guide, the theme park stated: 'Our policy has been updated to provide an even better service to those who need it.'
Disability campaigner Neil Coyle, of Disability Alliance said insisting visitors bring letters of proof was "not reasonable."
He said many disabled people would struggle to be able to afford a day out - and a doctors' note.
Three million people a year visit the theme park, owned by Merlin Entertainments Group.
Alton Towers told the newspaper its policy was reviewed with the help of organisations including Scope.
It added: 'We are sorry a customer was asked to book an urgent doctor?????????s appointment and we apologise.
'We aim to ensure disabled guests are treated with respect.'
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