Spark Whitening Stole money from our bank a/c, refused refund after return of goods Henderson Nevada

Sparkwhitening are complete fraudsters and need to be prosecuted.   We spplied for a so-called free sample  but had to pay for postage to the UK snd gave our account details which was our mistake.   Not only did they send the sample but the full course and took from our account the amount of £257.  Over the last two months we have asked for our money back as the items have been returned to Nevada and tracked as received by them,                   

To date we have not received from them one penny in refund. Why are these people allowed to get away with such fraudulent trading?? Why are the USA Authorities not prosecuting these fraudsters?  Why are they allowed to continue thus? Finally.  We are old age pensioners well into our 70's and cannot afford this loss of money.