pay a arm and leg for broken goods

My mother bought my sons a present at home choice, witch she is supporting for a lot of years.Present a double bunk bed. Short story, they deliverd at her house, they didn't erect the beds on my moms request coz it was a present and still had to be moved to my house. Im a mechanic and had one of these beds before, rocket science aint needed! At my house a week later after delivery I took out only first parts to build bed. Already was mark on one part,but didn't mind coz of exchange time. Went on building head and feet part of bed. Feet part went great, then head part, as I was tightening bolts the one bar broke off AT THE WELDING. Now home choice have all kinds of excuses, like they cant exchange because they didn't erect the bed, ****!!! My mom must pay R11869 on credit for their bad workmanship? NEVER!! They can come fetch their **** and never phone us again! My mom is phoning and struggling since 4/5/2015 but they quick to sell goods and to phone for there money. I will make sure my mom pays nothing, they can fetch their **** and I will buy my chidren beds at house and home or some other place.