Before purchasing my ipod a couple of years ago, I contacted the apple helpline which is based in Ireland. I explained my situation and asked if there were any solutions. I was asked "Can't you just cut the other headphone off".
As I was a little dismayed by this comment, I contacted the Equalities and Human Rights Commission to see if they were, in fact, breaking the law by not providing a solution. Unfortunately, because the ipod is a manufactured product, and not a service that is being offered to the service, there is nothing in the legislation that requires manufacturers or designers of products to make changes to their products, packaging or instructions. However, it is good practice for the company to make their products accessible to disabled customers.