Chargeback is your friend! If a retailer refused to refund me in these circumstances this is what I would do. Not only do you get your money back, it costs the retailed around £25. if more people used this perhaps retailers would get their act together.
The following link is info from Visa, and below is the text from FAQ for Mastercard.
www.visa.co.uk/how-you-pay-matters/chargeback-purchase-disputes.html?
Mastercard FAQ
Transaction dispute
Q: How can I dispute a charge?
A: Please contact the financial institution that issued your card to dispute a charge. Only your issuer holds your specific and unique information including what rights you have to file disputes. The dispute process agreed to by financial institutions that issue Mastercard or process Mastercard transactions is set up to allow the financial institutions to manage disputes with cardholders and retailers in a formal manner.
Q: Who do I contact if I never received an item that I purchased online or by phone?
A: If you did not receive an item that you purchased or if you received an incorrect item, you should first contact the retailer to try to resolve the situation. If you can't come to an agreement and you want to dispute the transaction, this must be done directly with the financial institution that issued your Mastercard.
Typically, there is a customer service number for your financial institution on the back of the card. You can always contact the Mastercard Assistance Center either toll-free at 0800964767 and we will connect you to your financial institution.
Q: I made a purchase but received the wrong item. What should I do?
A: If you purchased an item but received the wrong one, please contact the retailer to try to resolve the situation. If you and the retailer cannot resolve the issue, and you want to file a disputed transaction, this must be done directly with the financial institution that issued your Mastercard.
Typically, there is a customer service number for your financial institution on the back of the card that you can call. You can always contact the Mastercard Assistance Center either toll-free at 0800964767.
Q: How do I get a refund from a business that has filed bankruptcy?
A: If you used a Mastercard for a purchase from a business that has filed for bankruptcy, you can file a disputed transaction with the financial institution that issued the card. Typically, there is a customer service number for your financial institution on the back of your card card that you can call. You can always contact the Mastercard Assistance Center either toll-free at 0800964767.