DON'T BUY ONLINE FROM HI FI CORPORATION

I ordered an office chair online last week. The chair came on on Monday with missing parts. On the same day, 11 August, I emailed them to inform them I received a chair with missing parts. I also went onto my account and spoke to someone on the live chat. Then a last called me on Wednesday by the name of Tshegofatso Masekwane asking for pictures. I emailed her and on Wednesday and I am still waiting for her response. I called one of the branches to ask if I can bring in the chair, they said I can however they cannot give me another chair. I have exams on Monday and I need the office chair ASAP.

What should I do to get an office chair from Hi Fi Corporation that I have already paid for?

I do not want a chair in parts, I need the chair to come to me already put together looking exactly like what I ordered online.