what is happening with my steam iron?

my iron is only a few months old-- Tefal steam generator- GV7455. just recently it has started to get water bubbling up the steam pipe and spewing out onto my clothes , along with white calcified water and a huge amount of steam. the holes are also filling up with a calcium deposit. why is this??? I regularly clean out the anti-calc on the iron This is the reason why I had to buy a new one in the first place