Gas leak in mums house

Basically there was a gas leak in my mums house a few month's ago and she got lucky because it could have been so much worse but she didn't notice the smell my younger sister noticed but my mum kept dismissing it. It wasn't until my older sister came over that she actually phoned the gas man it was a big leak and i was soooooo angry that my mum kept dismissing it when everyone could have died if it blew