Merrell Hiking Boots size 4.5UK

Good Day
Brand new Merrell hiking boots. Worn only once as its to small. When hiking u should take a size bigger which I was NOT told. Its a size 4.5. Will Suit someone who is 3.5 or 4. Paid 1300 rand. Please make me a decent offer as I would like to buy another pair. Based In Cape Town.