Refusing to exchange or refund ****ed off

I have never seen anything like this in my entire life... Decofurn is making my life a leaving hell they are just after sales the horrible lady called Nerisa sold me a study table online when I got to the shop I told her is not what I wanted and she said the table will be available on the 13th Oct she will contact me I needed the table only to find that the table will not fit my daughter's room when I called and ask to exchange the table they told me that they are unable to exchange or refund my money.. Which I fail to understand that should you be unhappy with the item you bought you must not return is this furniture shop or underwear shop... I want my money back if they can not exchange the table... They are very unprofessional their services is like they are desperate for business... I am so ****ed off