"We apologise sincerely for this inconvenience."
Passenger Michael Harrison said the experience was both lengthy and unnerving.
"We got on the 3.50 pm crossing, approximately 10 minutes in the lights went out and the train stopped. We were told they needed to investigate an issue with the wheels," he told PA.
"It took approximately one and a half hours for them to investigate and obviously not find anything. They reset things and set off for another five minutes," he said.
"It happened again at which time we waited a further couple of hours to decide they couldn't see a problem but had to evacuate the train to another train."
After being evacuated through an emergency link tunnel, passengers walked through the service tunnel for about 10 minutes to reach another train, Harrison said.
Issues with the replacement train meant the 35-minute journey from Calais to Folkestone turned into a six-hour trip.
Another passenger said people began to panic while walking through the service tunnel.
"Several people were freaking out about being down in the service tunnel, it's a bit of a weird place. We were stuck down there for at least five hours."
Sarah Fellows described the tunnel as "terrifying".
"It was like a disaster movie. You were just walking into the abyss not knowing what was happening. We all had to stay under the sea in this big queue," she told PA.
"There was a woman crying in the tunnel, another woman having a panic attack who was travelling alone.
"They were expecting really older people to walk for a mile down the middle of a tunnel under the sea.
"I was panicking at one point and Border Force told us the tunnel had been evacuated one other time in the last 17 years, not recently," Fellows said.
Eurotunnel said the regular schedule was back up and running on Wednesday morning.
"Following yesterday's incident, we are now back to running normal services," it tweeted.
It took 13,000 builders six years to complete the 50km tunnel, which transformed travel between the UK and mainland Europe.
