Unfortunately, i don't think that you will be able to get a refund. Most shops/retailers have a return policy on software & Music/Movie Media that once the plastic sleeve seal is broken, you cannot return it (due to people copying then returning it).
If you don't want to fork out more money for a different antivirus program, or dont want to try they free ones, then post up the errors you are getting with the install and we "may" be able to help get it working.