Bedset from UFO - back pain

Bought a bed on Wednesday, they couldn't deliver the next day but said they would deliver on Saturday, I call them in the morning on Saturday to find out about delivery, they say they will deliver between 2-5pm, at 4:35 I receive a miscall, and then I return the call, it's missed, and the delivery driver named Philip calls me back, he asked "hello, did you lose your phone, I'm waiting here for 20 minutes". An absolute lie because I was outside anticipating their arrival (so inconvenient and last minute too) he was absolutely rude like he is making a free delivery.

Anyway, after 1 night of sleeping on the new bed I received, I'm experiencing extremely difficult back pain. Who do I contact with regard to this. I cannot keep this bed with the back pains I'm having.