Theo Robinson bagged a hat-trick as Southend thumped relegation-threatened MK Dons 4-0 at Roots Hall.The second-from-bottom Dons are now six points from safety with three games to go and never looked like troubling the Shrimpers.Chris Powell's side opened the scoring after 23 minutes when Robinson fired home after Dons goalkeeper Wieger Sietsma had parried a powerful shot from Dru Yearwood.Robinson was celebrating again in the 31st minute when he curled home a delightful effort from the left-hand side of the penalty area.Dons striker Chucks Aneke wasted a fine chance to get his side back in the game when he fired wide of the left post from 12 yards.Southend were able to take full advantage with Stephen McLaughlin heading home a left-wing free-kick from Michael Kightly in the 62nd minute.The hosts then wrapped up the scoring in the 76th minute with Robinson powering home from close range to complete his hat-trick before Shrimpers goalkeeper Mark Oxley superbly denied Aneke and Kieran Agard at the death.