"We are not prudes but this was ridiculous."
It was the couple's first cruise and things had already gone off to a bad start, when they were let waiting to board in high temperatures for two-and-a-half hours at Singapore's Marina Bay.
"When we finally got on the ship we first went to the bar for a drink because we were exhausted after all the standing around in the heat, "Bobby Jackson told the Sun.
"We were then shown down to our state room accommodation, which we were really looking forward to seeing."
When they first arrived at their cabin, the key card would not work – but after a third attempt, they were able to access their room and made the shocking discovery.
While the couple complained to the ship's guest relations manager, they were told there were no alternative rooms available as the vessel was full.
"We went back to the cabin and tried to go back in there but although the woman had left, the male was still there, " Bobby said.
"Two of the ship's crew in white uniforms eventually persuaded him to leave. He looked very sheepish."
When he asked crew if they knew him, he was told the man was a worker on the boat.
The couple were offered around $190 of credits to spend on the ship, but were "insulted" by the offer.
And things only got worse on this "dream cruise" – two days later, Mary became ill with a stomach bug and spent most of the ship confined to her cabin and was put on an IV drip.
After returning home, Bobby and Mary wrote to Florida-based Norwegian Cruise Line, but were still unhappy with a follow-up offer of £200 ($383) each in credits towards another cruise with the line, if taken this year.
The cruise line said a full investigation had taken place and appropriate action was taken.
In a recent survey by British consumer advice magazine Which?, Norwegian Cruise Line was found to be the second-worst cruise company, with a satisfaction rating of 66 per cent.
