You are right to complain.
If their goods can't be carried in transit in a car boot safely, without a warning printed on the can, threaten them with court action. Would this also happen inside the car? A child could be injured or an accident could happen if it distracted the driver when it exploded.
Stick to your guns. Try Customer Service at Tesco H.Q. Persistance usally pays off with these people in most cases.
If all else fails do what I do...lie.
Saying your cousin is a researcher for BBC's Watchdog programme usually helps me.
