Google is sending early adopters of Google Wallet emails in an effort to remind them to request a refund on the unused balance on their Google Wallet prepaid cards. The prepaid cards, which were discontinued on October 17, can no longer be used in conjunction with Google Wallet, and balance information is no longer available in the Google Wallet app.

Users have until June 1, 2013 to request this refund – and after that, they’ll have to deal directly with Money Network, which probably won’t be a smooth as dealing with Google. Users can request a refund by visiting a special website and providing Google with the IMEI or MEID number on the phone associated with the Google Wallet account.

Many early adopters of Google Wallet got a $50 promotional credit on the prepaid card, while those who started using the service a bit later received $10. Even though this credit was intended to familiarize people with NFC payments, it appears that Google is not distinguishing between promotional credits and money that users loaded onto the prepaid card themselves.

Users also have two ways to receive the refund: a physical prepaid card that will be delivered 7-10 days after a refund request is submitted, or a paper check that Google says can take up to two months to process.