OK, might be worth disconnecting battery, and leaving it disconnected for half an hour - but make sure you have your security code for the radio/SatNag.
But unless the batt is fully charged, and can keep its full charge, you will continue to get these issues.
Is yours a standard 200PS GTI, or a 230PS Ed30 or Pirelli? Because the standard GTI should have had a 72Ah battery - but many were fitted with a lower spec 70Ah (including mine - which was fully loaded with DSG, heated seats, sunroof - all electrically 'demanding'!). Do a search for battery issues (use the 'Advanced Search', then use my forum username [but not as thread starter], and just select the mk5 section, with child board).
HTH