Dean Parrett's stoppage-time penalty capped a stunning comeback as Wimbledon fought back from 2-0 down to win 3-2 at relegation rivals Walsall.Walsall led after just six minutes as Jack Fitzwater glanced Erhun Oztumer's free-kick past keeper George Long via his outstretched thigh.They doubled their lead on the stroke of half-time when Julien Ngoy flicked a ball over one Dons defender before outsprinting another to slot a cool finish under Long.But Nicky Devlin's rash challenge on Andy Barcham handed Wimbledon a lifeline two minutes into the second half.Unlucky Walsall keeper Liam Roberts saved Lyle Taylor's penalty with his legs and palmed away the loose ball only for Joe Pigott to slam home from close range.Taylor then fired an acrobatic volley off the post but latched onto keeper Long's 65th-minute clearance to thump home a superb strike from just inside the box.And Wimbledon won it deep into stoppage time as Parrett lashed home from the spot after Kory Roberts fouled Taylor.Victory pushed the Dons above Walsall, with the sides sitting four and three points respectively above the drop zone.