It could be that the email was ambiguous (because the refund amount was not stated in the email) and he'll get back only $10,000 total (only $25 from the first

It could be that the email was ambiguous (because the refund amount was not stated in the email) and he'll get back only $10,000 total (only $25 from the first deposit), in which case he's actually purchased $10,000 worth of bonds, but he'd only find this out in 8-10 weeks. Shoddy software like this undermines general trust in the government.