According to the Australian Consumer Law, we are not required to provide a refund or replacement if you change your mind.
You may be entitled to a refund or exchange if an item has a major problem.

This is when the item:

• has a problem that would have stopped someone from buying the item if they had known about it is unsafe
• is significantly different from the sample or description
• doesn't do what we said it would, or what you asked for and can't be easily fixed

If the problem is not major, we will repair the item within a reasonable time. If it is not repaired in a reasonable time you can choose a refund or replacement.
Please keep your proof of purchase - e.g. your receipt.

More details here: