If you haven't already, you should get the full reasons for the decision, and make sure that they took everything into account. If there was something that wasn't taken into account, then its not a bad idea to contact the deciding officer and ask for the decision to be reviewed. If that doesn't reverse the decision, then you can appeal, although this can take anything up to a year.
Depending on the medical nature of the decision, you might be able to apply for Disabilty Allowance, as there is a different medical test involved. However, Disability Allowance is means tested.