Rochester Furniture – faulty bed set

I bought a Base & Mattress (Sealy Bordeaux 152cm)set on 20/3/2018 at Rochester Parkview Pretoria. 8 Months into my contract the whole mattress collapsed in the middle, the new bed has collapsed also. So I went back, Sealy phoned me 20/12/19 I must pay R1400 to exchange because guarantee expire.This is a new mattress that is a year old, and is damaged.