Passengers unable to find accommodation slept in the airport
British Airways says 12 more short-haul flights to and from Heathrow's troubled Terminal 5 have been cancelled, taking Saturday's total to 66.
The further cancellations were caused by problems with the baggage system, BA said. The disruption is due to continue with 37 flights cancelled on Sunday.
Passengers on flight BA0662 to Larnaca have remained on the tarmac since 0830 GMT due to a baggage mix-up.
BA has also retracted its £100 limit for delayed passengers' accommodation.
One passenger on the delayed Cyprus flight, Elizabeth Drury, told the BBC they had now been told by the captain they would be leaving without any luggage.
They had been told this was because some of the bags initially put on the plane had not been screened properly.
"The whole experience has been meltdown," she said.
After facing criticism over its limit on hotel accomodation for delayed passengers, BA said it would cover "reasonable costs" .
On Thursday evening, leaflets were handed out to passengers whose flights had been delayed or cancelled, saying they were entitled to £100 compensation for two people sharing a hotel room.
Staff at the £4.3bn terminal's hotels reservation centre said the minimum rate on Thursday night for a double room was £250.
However, on Friday night, BA announced the policy had been abandoned and it would cover "reasonable costs".
The Times claims BA could be facing fines of up to £5,000 per passenger because the letter breached European regulations on compensation.
Under new rules, which came into force in 2005, an airline is obliged to supply meals and refreshments, along with accommodation if an overnight stay is required, when a flight is delayed.
Simon Evans, chief executive of the Air Transport Users' Council (AUC), told the newspaper: "On the face of it, the letter is a clear breach of the regulation because it does not explain clearly what people are entitled to.
"The way it was worded would make some people cautious about even booking into a hotel."
A BA spokeswoman said: "We don't believe we did contravene any regulations. We are compensating customers who contact us in accordance with the regulations and this includes accommodation, transport and food."
More than 100 flights at the new terminal were called off on Thursday and Friday because of earlier glitches with the baggage-handling systems.
BA has set up an information line for T5 passengers: 0800 727800
Have you been through Terminal 5 today? What was it like? Do you work there? Tell us about the new terminal at Heathrow airport.
You can send pictures and video to: firstname.lastname@example.org or to send via MMS please dial +44 (0)7725 100 100.
Do not endanger yourself or others, take any unnecessary risks or infringe any laws.
The BBC may edit your comments and not all emails will be published. Your comments may be published on any BBC media worldwide.