Hope this is not too late... You are entitled to a replacement by consumer law so long as the fault was not caused by negligence on your part. I imagine this chip has been bought from a fairly small company as larger ones usually have no problem with returned goods.
Often smaller companies will tell you that they won't accept a return because they know that most people will walk away. The best thing you can do is go back and demand a replacement after taking a look at consumer law, being able to quote something directly will often change their minds
If they still refuse to give you a replacement just report them to the office of fair trading (or whatever it's called these days) or at least threaten to. Don't let them push you around, you paid good money for the product you purchased!