Hi @dogzbody,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Just so we can ensure we are on the same page, can you advise which specific mixer tap you've purchased? Was it the Estilo 35mm Chrome WELS 5 Star 6L/min Coil Dual Function Tall Pull Down Sink Mixer?
If so, then small bits of plumbing debris from installation can sometimes clog the flow selector, so it’s worth unscrewing the pull-out nozzle and giving it a good rinse or flush.
Another possibility is a stuck diverter mechanism, as the button on the head is linked to a small plastic or rubber diverter that can jam straight out of the box; pressing the button firmly a few times while the water is running or soaking the head in warm water can often free it up.
If neither of these steps solves the problem, the spray head itself may simply be defective, in which case you can return to the store of purchase with your receipt for a replacement.
Let me know how you go. I am happy to assist further if required.
Jacob
