A couple are suing Tui UK Ltd after they claim they experienced bed bugs and were left vomiting after a honeymoon cruise with Thomson.
Philip and Janice Stephens honeymooned on the Thomson Celebration cruise ship to Turkey in September 2014.
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But, after a couple of days they said they noticed bed bug bites and their room had to be fumigated twice.
They also said their food was allegedly lukewarm and undercooked.
Since her return to the UK, Janice has developed chronic fatigue syndrome and has had to take voluntary redundancy from work as a result of the chronic fatigue she suffers, the exact cause of the chronic fatigue remains under investigation and may be as a result of a post viral infection.
The couple are hoping to win compensation for the holiday through lawyers Irwin Mitchell.
Jennifer Downing, an expert international personal injury lawyer at Irwin Mitchell, representing Philip and Janice, said in a statement: "Clearly this was supposed to be a relaxing and romantic trip for Janice and Philip but they were left unable to enjoy the facilities they had paid for due to the illness they experienced.
"Understandably, Philip and Janice want answers about the illness Janice suffered, which continues to affect her to this day, and to understand why their honeymoon cruise was ruined. We have now issued formal legal proceedings against TUI UK Ltd."
Janice said that the ship "wasn't up to standard", and descried her illness as "horrendous".
She added: "The fact that it continues to affect me to this day has just added insult to injury for me."
A Thomson spokesperson told MailOnline Travel that they were sorry to hear of the couple's bad experience, adding: "As this is now subject to legal proceedings, it would be inappropriate for us to comment further.
"We closely audit all resorts to which we operate to ensure that health, hygiene and comfort levels are maintained in line with industry standards."