Bad customer service

I made an online purchase of a size 8 sandal/slide, payment went through, got the conformation email afyer money went out of my bank account.

Few sdays later, js becore the event I was buying the item for, I get an email telling me that they had a "technical glitch " and I must choose from the colours they have. I reply which colour I want and get told I can only get money bac****! I bought a dress and matching handbag to complete the outfit now what must I do with all this??? I am dik of Melissa, to think I liked them so much... and I do not want my money back, I want the Black floral Beach slide or Rosegold shine slide and that's it!