I need to pay for their mistakes and bad service

I order bed legs from them online to lift my bed. The spesifications on the website was clear about the lenght BUT when I received it it was completely wrong. Instead of sending me the product I order they send me a small one. I now need to pay for the courier to send it back and get a refund because they mad a mistake!! Not only that I mailed them and phone and no respons for 3 days. I eventually got hold of someone thru their whatsapp channel but sill very unprofessional and not good service at all.