Officials from Vauxhall car company have told MPs that they have only investigated 59 out of 287 fires in the Zafira B model since the problem came to their attention through media reports in 2015.
The Transport Committee questioned officials about two recalls of the vehicle after several fires which were blamed on a defect in the heating and ventilation system and improper repairs to the people carrier's blower motor resistor.
Vauxhall's vice president of quality in General Motors Europe, Elvira Toelkes, director of global safety and field investigations, Thomas Berenz, and head of government relations and public policy, General Motors, Helen Foord appeared before MPs to discuss the issue.
Ms Tolekes told the Committee that the company was aware of 287 fires and had so far investigated less than a quarter but could not get access to the other vehicles involved because they had been scrapped or the customers did not respond to letters.
MPs also demanded answers about the way Vauxhall handled customer complaints about the fires.
All of the firm's representatives admitted that they had not personally met any of the people affected but "apologised" for what they had been through.
Ms Tolekes urged Zafira B owners who have not brought their vehicle to be repaired since the recall to contact their local dealer as soon as possible.