I purchased a £19 voucher for some Jewellery from an on line site for Jewellery worth £119. I followed the instructions, entering the voucher number but when the invoice came through and I checked my Credit Card I had been charged the full amount instead of just the P & P. I have e mailed several times asking for a refund but all I have got is an e mail telling me the goods will be delivered within 21 days - they have obviously not read my e mails. What can I do?