Ian Rowe’s side trailed 2-0 to goals from Zak Goodson and a Michael Perks own goal on 38 minutes.
But Perks redeemed himself with a header just before the interval to reduce the deficit.
The Robins had chances to extend their lead without success and were punished on 70 minutes when James McGrady converted a penalty for Sporting to level the match.
Sean Williams then fired in a third on 82 minutes to complete a remarkable comeback by the hosts.
Goodson spurned a glorious opportunity two minutes later and that miss was made academic on the stroke of full time when Luke Yates scored for the second successive game.