Office Chair Nightmare

I bought and collected the Office Chair on 11 august only to find out that is unfit to my deck table is too BIG, on the 13 August i return the office chair , only was advised that they wont accept it because its already assembled, how i knw if is the wright size without assembled it , they did not advise me about Gaslift that is unrepairable, they only said i must ref to return and refund policy which i did there is no return policy for office Chairs, i need to know whet must i do with this Chair they did even bother to offer a voucher or to exchange it they where not even interested on my issue can this Company refund Me i budgeted my money so hard pls