Rob....as far as I know, they have a 2 year warranty on the buggy...one assumes that the battery being dead after only 3 months would be an automatic replacement. Give them a call...they're in Nunawading (11 Maurice Ct) 9873 4433.
That might be better.
I spoke to GCO this morning. They said to drop it off and have a result in 3-5 days.
Be a nightmare getting to Narre Warren after work then back home