Already used-up Synapse activation code

Hello,
I recently bought a new Razer Kraken Tournament edition headset.
I bought it from official shop ( not Razer, Alza.cz ) and I bought a piece which was already used by another customer, who returned them after a short while.
The point is, that at the e-shop I was told that this headset + everything within it was already used, but the whole set is completely undamaged and that its ready to my full use.

Well, thats true, but the most important thing, the Synapse activation code - it was already used by previous customer.
So, what am I supposed to do now? Should I return them to the store? I can provide photo evidence which confirms that I really bought the headset officialy from a certified store.

Sorry for grammar mistakes ( im not native speaker) and thank you kindly for any help!