Jade Marshall visited the Goodfellowship Inn, Hull with her family to celebrate her birthday on 17 August, the Daily Mail reported.
The newspaper said Marshall was "horrified" when she began eating her veggie burger to discover it was allegedly a meat pattie.
She then claimed there was an argument between her and the waitress, who stated the burger was vegetarian.
Veggie burger
Marshall refused to eat the burger and said she was not offered a refund at the time of the incident.
Stating that the pub had "ruined her birthday meal", she also claimed the waitress shouted at her. Marshall also said the venue had no customer service skills and was “far from vegetarian friendly”.
However, a Marston’s spokesperson said: “The management of the Goodfellowship pub can confirm Marshall was served a vegetarian burger."
No evidence
The spokesperson added: “Soya-based vegetarian burgers are quite distinct in their taste and texture, and the team are clear in their minds that she was served correctly so we believe this is where the confusion lay.
“There has been no photographic evidence or witness evidence provided by Marshall to prove otherwise and it was confirmed as a vegetarian burger with her, during her visit and since.
“The pub has since apologised for how Marshall felt regarding her experiences and has offered vouchers as a gesture of goodwill, which she has accepted.
“Since her initial complaint, we have been in direct contact with Marshall to help to resolve the complaint and fail to understand what more the pub could have done in this situation.”