Bad service

I lay-buyed a bed at Sleepmasters Southgate when I went to pay the balance last Tuesday, I was told they no longer have the bed. I agreed to take a similar bed for an extra R500 otherwise I had to wait till Jan 2021. The problem started when there's was no delivery I had to call the shop and was told they miscalculated and I must pay in another R600 which I told them I don't have and requested cancelation of the deal. After numerous calls to the shop the manager would promise to call back but never does. I went to the shop to fill in the cancelation for a refund, the attitude I got as if I was responsible for their negligence after I was told everything was in order. I have never experienced such bad customer service with no apology for all the inconvenience they caused me.