I want my door replaced and buildit to pay for labour

On 25th September i bought a door from buildit melmoth , the door was installed and i paye R350 for labour. Saturday morning 13th October the door was cracked into two pieces . i sent my younger sister with pictures to take to buildit to show the the door didnt last . I had paid R1300 for that door to not last not even a month. she was told that the door will be replaced but she needs to take out the other one. my question is ,who needs to take it out. does this mean i must pay for labour another R350 where as build it sold me poor quality door? this morning when i phoned to enquire that ,some guy answered the phone and refered me to Dan , that Dan guy told me its none of their business and they wont even replace that door , he was too rude that he even dropped the call on my ear. i want that door replaced and also i dont expect them to replace it with same poor quality make they sold me. and they must come with someone to do ot or that should pay for labour.