VALE put in a valiant performance but were ultimately undone by defensive errors and a lack of quality in front of goal against an in-form Heys side, who had won their last six league games.
The visitors started the stronger and were unlucky not to score on five minutes when a well-worked move saw Sam Ernst bring a fine save out of Rob Sadler.
Leighton Mills and Ricardo Williamson also went close in the early exchanges.
Already shorn of first-choice strikers Gareth Gardiner and Marvin Browne, Vale were dealt a further blow with the loss of Mills to a knee injury after 15 minutes.
Laying siege on the Vale goal it seemed only a matter of time before Heys took the lead and they had their chance early in the second half but George Powell blazed his penalty effort over the bar.
Minutes later midfielder Danny Eyres drilled home a low shot to give Prestwich the lead and Vale were made to rue missed opportunities when a sloppy pass from left- back Craig Thomas landed straight at the feet of Chris MacKay who buried his shot into the top corner.
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