The Blues will now face Ryman Premier League side Harrow Borough on Saturday as they bid to make the 1st Round.
The Ryman Division One side slowly grew into the game and forced Lewis Ward into two quick saves forcing Alex Akrofi’s snap shot over the bar.
Hastings continued to press and got their reward on 24 minutes as Sam Cruttwell saw his header sneak past Ward from a corner for his second goal against the Blues in seven days.
Cruttwell continued to worry the Blues defence with some fine free-kicks which were testing the depleted Margate back-line, however some resilient defending from Brett Johnson and Manny Parry denied the hosts from further extending their lead.
Margate grabbed an equaliser four minutes before the break after a fine individual run from Daniel Akindayini who raced past two Hastings United defenders before curling a delightful effort past Pidgeley which hit the inside of the far post before hitting the net to level the scores.
Bull’s side could have taken the lead before the break as Akindayini squared across the six yard box just ahead of Buchanan who couldn’t quite turn the ball home.
Just before the hour Mark the visitors felt they should have been awarded a penalty as Alex Osborn was wrestled to the ground only for the referee to blow his whistle and book Osborn for an apparent dive as Margate protested furiously.
Time ticked away and extra-time seemed inevitable until Hastings United almost stole the win in the 90th minute as Jack Harris saw his low shot go just inches wide with the final opportunity of the evening in normal time.
Margate started extra-time strongly and should have gone ahead in the first five minutes as Buchanan rolled a chance wide from 6 yards on what looked to be turning into a frustrating evening for the Gate.
The second half of Extra-Time was even better by the Blues as Osborn, Matthew Johnson, Cash and Akindayini forced Pidgeley into action before the Gate won it with five minutes left as Osborn’s short was pushed away but only to the feet of Buchanan who made no mistake from five yards to send the Blues through.
Margate will face Harrow Borough on Saturday in the 4th Qualifying Round of the Emirates FA Cup with kick off at Earlsmead at 3pm.
Travel details will be released later today.
MARGATE: Ward, Sessegnon, Tumwa, M. Johnson, B. Johnson (Mambo), Parry, Moore, Cash, Buchanan (Phipps), Akindayini, Osborn
Subs Not Used: Bull