Things did not look rosy for the visitors when Scott McGleish converted a tenth minute penalty to put Colchester ahead.
However, three goals in a 14-minute spell turned the game on its head with strikes from Stephen Brooker (13) and Michael Cummins (27) sandwiching an own-goal from Wayne Brown (24).
Marc Bridge-Wilkinson (pictured) put a gloss on the scoreline a quarter of an hour from time as Vale moved into fifth spot.
Bournemouth produced a magnificent display at Dean Court to dispatch Wrexham 6-0, with striker James Hayter netting an incredible hat-trick in just two minutes and twenty seconds.
The hosts got off to the perfect start when Stephen Purches pounced after just three minutes, and Warren Cummings doubled the advantage on the stroke of half-time.
Warren Feeney put the result beyond doubt with a third just before the hour mark, but there was still time for a dazzling individual salvo from Hayter.
The hit-man came off the bench six minutes from time to replace Stephen Fletcher, and amazingly was celebrating a treble just over two minutes later after goals on 85, 86 and 88 minutes.
Grimsby boosted their hopes of avoiding the drop after a last-gasp Simon Ford header gave The Mariners a 3-2 home win over in-form Luton.
Things seemed to be in hand for Mike Newell's men who took the lead through Steven Howard after 19 minutes.
A double from substitute Phil Jevons (55 and 69) - the second of which was a penalty - put the hosts in the ascendancy though, before Howard pounced for his second of the night ten minutes from time.
However, just as matters looked set to end all even Ford popped up to head home Darren Barnard's free-kick for a crucial victory.
Rushden moved ahead of Tranmere after seeing off Rovers 2-1 at Nene Park.
Tranmere's Daniel Harrison equalised Onandi Lowe's opener and Eugene Dadi then struck a post for the visitors.
But moments later Rushden got what proved to be the winner when Gary Mills netted his first goal for the club.
Match summaries:
Bournemouth 6-0 Wrexham
Colchester 1-4 Port Vale
Grimsby 3-2 Luton
Rushden 2-1 Tranmere
