I bought a computer chair from Argos about 2/3 months ago, the handles cracked & broke & caused hubby to fall?

My kids bought me a swivel padded computer chair too from Argos ,, Has 4 legs with wheels on .. In turning one day , one leg , its a plastic moulding, snapped and the chair went up in the air, as did I .. Suffered a badly bruised hip and bum,,, lucky no breaks ,, Took chair back to argos( chair had been used for 6/7 months) and they exchanged it immediately with no arguments .. Very apologetic ,, its not just rights involved,, goodwill and fair trading come into it too .. Lots of shops do more than is legally necessary .. By the way,, approach them reasonably, dont go in ranting and raving or you put their backs up and you wont get very far ,, Just say,, " we have a problem and wonder if you can help us? you will get far more help ..