General Motors Canada tried, but failed, to stop Unifor from airing a TV commercial lambasting the automaker during the Super Bowl.

The 30-second ad, which was broadcast on Canadian TV stations during last night's game, calls General Motors greedy and "un-Canadian."

It comes after GM announced plans in November to close its Oshawa plant by the end of this year, eliminating about 26-hundred jobs.

GM sent a cease-and-desist letter to Unifor telling it to stop using the ad, but the union says it will be buying even more airtime from other programs such as the Golden Globes and Maple Leaf games.