Can I claim my money back, online rip off?

I checked my bank to see that �150 was taken out on 22nd july to an american company. It turns out that when I allowed my 8 year old neice to buy a �1 trial of dietary supplements for her mum that apparently she ticked to agree to terms and conditions and therefore this company can keep this �150! how can i get my money back of them, Im distraught as I now cant pay my bills this month