Wrong product delivered

On the 7th May I went in Fair Price at Kaisha Park and Mr Tovhowani Magoma helped me. I was Looking for a 3/4 Bed and he said yes that is a 3/4 bed.After considering I paid and later that day the bed was delivered. The bed was that was delivered was a double and not a single. I phoned immediately the store and spoke to Mr Magoma and he said it's the right bed my son must use it. The bed is so hard and it feels like a base alone. I went to see Mr Magoma and he told me we paid for a double bed bed after I told him we want a 3/4. I left the store saying that I logg a complaint. The bed at the bottom is falling apart and it's not even 2 months. How can any person let people deliver a bed that we never ask for and now he is still saying we ask for a double bed. This is the worst bed ever made. I want the bed replaced and they need to come and fetch this bed. He made me and my family feel like ****s after I kept on asking is this 3/4 and also asked about 3/4 headboards. He still told us we can buy a double headboard and cut it shorter and yet he let them deliver a double. Please can a manager of Fair Price resolve this.