Weak bottle exploded

My friend and I bought 2 x 1ltr Carling Black Labels from the Spar in Vredekloof Cape Town. When we got home and walked up the stairs, the one bottle exploded!!! This is not something that I expect to happen. It was only lucky that they were in a packet if we carried them loose who is to say where the glass would have ended up. Someone could have been seriously hurt. When we opened the other one it also made an exploding sound.... not great! Not only did we loose a well deserved beer but at R20 a bottle we expect to buy quality. I am not sure if the bottle had a weak spot but I do have pictures of the bottle as well as the 2 big pieces of glass from where it exploded. I would also like to add that at no point was the bottle banged or dropped and it was not warm out, the bottles was cold and in the fridge at the store. We have been Black Label drinkers for the beter part of 18 years and this has never happend. Please can someone advised how to rectify this. Regards Brigitte Schwerdtfeger