On a heavy pitch which only just passed a 9 am inspection, it was Slimbridge who started the brightest in a dour first half which lacked very little goalmouth action.
The home side had a penalty appeal ignored by referee Niall Clinton when Jaden Maddock caught Jack Smith in the face with his boot as he stooped down to head the ball, resulting in Smith leaving the field with a broken nose.
On 32 minutes the Swans took the lead when Josh Beadle found Yeshaya Lomotey who unleashed a terrific shot from 25yards which went into the top corner of the net leaving the home keeper with no chance.
Slimbridge were pressing for a second goal now and when Edji Mbunga laid a lovely ball into the path of Dan King the Gloucester City youngster let fly from 18 yards only to see his shot palmed away for a corner.
Maddock then went on a good run up the right and his cross found Mbunga whose powerful drive was blocked by a defender. A bad back pass by the home side left their keeper in big trouble and as the Swans tried to take a quick corner with no defenders back the keeper deliberately hoofed the ball away resulting in him being cautioned.
Totton had obviously had a halftime talking to as they came out looking a different side in the second period. The turning point in the game came on 53 minutes when Mbunga was sent off for retaliating to a foul, pushing his opponent with two hands leaving the referee with no option but to dismiss the Swans forward.
Slimbridge paid for this lack of discipline and the home side were level ten minutes later when a good cross from the right was headed home by Justin Bennett.
The Swans were under the cosh now and defended brilliantly against a rampant home side who were pushing for the winner.
Superb blocks by Christien Turner, Joe Noakes and Korey Pring denied the home side a sniff at goal and a couple of superb saves by Lewis Adams kept the score level.
With the referee notifying a minimum of 5 minutes of stoppage time the Swans continued to hold on but on 94 minutes disaster struck when a low cross from the right was tapped home at the far post by substitute Eddie Perrett to send the home side delirious and leave the Swans a very dejected outfit.
Manager Lee Driver-Dickerson must now try and lift his squad for some important games coming up starting with a home game against high flying Yate Town on Saturday, followed by a visit to fellow strugglers Mangotsfield Utd on Sat 22nd and then another home game versus League Leaders Blackfield and Langley on Sat 29th.
Slimbridge: Adams, Maddock, King, Pring, C Turner, Noakes, Mendes, M Turner, Mbunga, Lomotey (Dunbar 81), Beadle (Smith 63)
Supporters Man of the Match: Joe Noakes