Stuck with an uncomfortable mattress?

My aunt bought a mattress from this outlet in Centurion. After it was delivered on Saturday, two weeks after she paid for it, she slept on it for one night but found it extremely comfortable. She is 76 and quite delicate, therefore she needs a mattress that's fairly soft yet provides enough support. She gave the mattress, which she had covered with a mattress protector, another go on Sunday night, but hardly slept at all. When she phoned the shop on Monday morning to return the mattress, she was told they don't take mattresses back if they'd been removed from their plastic covering and have been slept on, but offered to redo it with softer foam. She has declined their offer, but they now refuse to take it back and refund her, even though we've contacted LegalX and are perfectly within our rights to demand a refund.