For anyone interested.. seems like its for New Users only. Hope it helps some of you
Receive $15 FREE credit towards your first goCatch ride in July with this promotional code: GOJULY
or
Click Here: http://bit.ly/gojuly15
New users only. Limited to the first 2,000 users. Unused Credit expires midnight (E.S.T.) on Thursday, 31st July 2014.
works on existing accounts