CALGARY -- The company that runs the Air Miles loyalty rewards program is the target of a proposed class-action lawsuit.

A statement of claim filed with the Court of Queen's Bench this week alleges LoyaltyOne Co. made "unfair and unilateral" changes to the program's terms and conditions, including that miles racked up before December 31, 2011 expire at the end of this year and miles collected after that are to expire five years after they are earned.

The proposed suit, which has not been certified, claims users were not given adequate notice of the changes and that the company has made it difficult for miles to be redeemed before their expiry.

"The net result is that Air Miles' conduct will result in a large number of the class members' miles expiring, resulting in a significant loss to the class, and a corresponding large windfall for Air Miles," the claim states.

Air Miles are earned by shopping at participating retailers and are meant to be exchanged for flights and other rewards. The suit estimates 10 million Canadian households belong to the program.

The representative plaintiff in the case is David Helm, a Red Deer, Alta., man who had been saving up miles since 1990 for a "dream trip" to the South Pacific that he otherwise could not afford.

The statement of claim says Helm found out about his Air Miles' impending expiry from a neighbour in 2014.

"As a result of the expiry of his miles, Mr. Helm realized he would not be able to earn enough miles in time for his dream vacation, despite the fact he had been earning them for many years."

The statement of claim says users wanting to redeem points before they expire have had problems doing so because of "unduly long" wait times on the phone. As well, it says the website displayed reward items users did not have enough miles to purchase, but not those that were within reach.

"The amount of miles required for an item seems to be escalating so that they're always close but not quite there," said Andrew Wilson, a partner at JSS Barristers, the Calgary law firm handling the proposed class action.

"They go out and get further miles and then when they come back in to get the same item, it has gone up yet again, requiring them to go out and get even more miles."

Should the case be successful, Wilson said LoyaltyOne should reinstate expired miles.

"Failing that, some form of monetary compensation for the lost miles and perhaps some form of monetary compensation for the annoyance that program members have faced when attempting to redeem their miles over the past six months or so," he said.

LoyaltyOne did not immediately respond to an interview request.