What remedies are available to customers?

It depends on what exactly you need a remedy for. The basic principle under The Sale of Goods Act and The Supply of Goods and Services Act is that products must be "fit for the purpose for which they were intended" and that the description of them must be accurate. An example of a product not being fit for purpose is a coat which is described as being waterproof, not actually being waterproof. If you have bought a product which is not fit for purpose for whatever reason then whomever you bought the item from is legally obliged to offer to repair a faulty item free of charge, or more realistically replace the item or offer you a refund. Even if you bought the item during a sale and the store say it's their policy not to offer refunds on items bought in a sale - your statutory rights mean that the store is still legally obliged to offer you a replacement or refund if the item was faulty (except perhaps if it says "sold as seen" on the label) or if it did not match its description. You do not even need a receipt if it is clear where you purchased the product - e.g. a TESCO branded product - TESCO would have to replace or refund without a receipt. But if you do not have a receipt for a product that could have been purchased in numerous different shops then you cannot expect the store you bought it from to take responsibility for it, unless you can show evidence in the form of a debit/credit card transaction.