Although it's been said that it's not possible for the seller to issue you with a partial refund, there have been posts on these forums recently whereby other responders have said that if the seller offers you a partial refund then you have to review the seller's offer via the eBay Resolution Case and accept it if you are happy with the amount offered in relation to the partial refund. If the seller were to do that then you could just accept the offer and the seller could issue the partial refund. Alternatively, if the seller cannot do that for some reason then he could always issue a partial refund via PayPal, although he may not be to keen on that option as he could get a defect for refunding via PayPal.
Whatever you do, do not allow the seller to persuade you to close the case on the promise that he'll issue you with a partial refund if you close the case. You have far more clout with a case open, and none whatsoever with the case closed, so if you were to close the case on a promise and the seller wasn't true to his word then you would not be able to re-open the case. If that were to happen then you could open another case against the seller via PayPal, but why give yourself all that hassle when you could probably just force the seller's hand by standing your ground and refusing to close the case until the matter is resolved to your satisfaction?
At the end of the day if the seller justs messes you around and you get the sense that you are getting nowhere then escalate the case to eBay when you get the chance to do so and let them decide. eBay tend to decide cases in the buyer's favour most of the time, so if you did need to do that then you'd get your money back, albeit in the form of a total refund, as opposed to a partial refund, so it's not in the seller's interests to mess you around.
