Hi there Muffin Bandit. If they are Butch products, email the team through this site, with the product name, size and if you still have them, the best before dates and production time codes and the store involved and they will contact the supermarket and deal with it.
If they are from another manufacturer, then contact them and provide the same details I mentioned previously and they will investigate the suppliers, (either Progressive of Foodstuffs) and their processes for chilling, containment and shipping, and will find out why this has occurred. They will usually also work with the supermarket management in order to stop this issue arising in the future.
This is the best way of going about it and it would be a good idea to let the company know just how supermarket staff treated you, when you requested replacement/refund and they will also make sure that should not occur again.
Good Luck!