If you mean a collection item, then ebay sends a code to your phone and the seller scans it with their phone. Only apples if both Buyer and Seller are using he Ebay App.
If you mean the code to collect from Argos, then you will have to ask Ebay for, Long winded system which is best avoided. Argos tell ebay item has arrived, Ebay give you a code, but there frequently are delays.
