Roddy Lemba bagged his 15th league goal of the season to put 'Side ahead, as the hosts went into half-time ahead.
Bengal hit back in the second-period with a brace from Eaia Embalo giving Imrul Gazi's team the three points.
Michael Walther's Sky Blues remain in 16th place with four games remaining this season.
'Side are next back in action on Saturday at Cricklefields in an 'away' fixture against Ilford. Kick-off for that match is at 3pm.
Updated 08:38 - 18 May 2018 by Adam Dennehey