
<?php $writeDate = $row_Recordsetcustomers['date']; ?>
Then in the form use:
<input name="hf_date_<?php echo $RepeatSelectionCounter_1; ?>" type="hidden" id="hf_date_<?php echo $RepeatSelectionCounter_1; ?>" value="<?php echo date ( 'Y-m-d H:i:s' , $writeDate); ?>" />
<?php
$writeDate= strtotime ( '+ 7 day' , strtotime ( $writeDate) );
?>

Thanks will give it a go
john