Wall charger exploded (again!)

I've just had the second of two samsung chargers explode while plugged in at the wall. Both came with Samsung phones new and both have exploded within 4 months of each other. Is there anywhere to report this? Both times it was a very loud bang, a flash of light, and then a burning smell although there was no fire. I'd seen previous posts where Samsung had claimed this was a rare event so I wrote the first time off as a one off event but it has happened again with a seperate charger. Both chargers are pictured.