Nordi Travel, which is based in Livingston, was punished by the Traffic Commissioner for Scotland after being called to a public inquiry.
Officers monitored 71 journeys between the West Lothian town and Ocean Terminal over the month of May, with more than a third of them either running late or not at all.
Examiners also noted that there were delays in assessing the roadworthiness of some vehicles.
Directors Norman and Diane McCulloch said a driver shortage was making it difficult to adhere to timetables and that they planned to shut down the firm.
Commissioner Joan Aitken said: “Given the manner in which this operation came to an end and the abrupt cessation of registered services, disqualification is something which I could have in mind.
“However, the directors have stated that they have no intention of bus or coach operating in the future.”