I believe the relevant code may be in class-wcv-simple-auctions.php:

WCVendors_Pro_Form_Helper::input( apply_filters( 'wcv_simple_auctions_start_date', array( 
			'post_id'		=> $post_id, 
			'id' 			=> '_auction_dates_from', 
			'label' 		=> __( 'From', 'wcvendors-pro-simple-auctions' ), 
			'class'			=> 'wcv-datepicker', 
			'placeholder'	=> __( 'From…', 'placeholder', 'wcvendors-pro-simple-auctions' ). ' YYYY-MM-DD ',  
			'wrapper_start' => '',
			'wrapper_end' 	=> '', 
			'custom_attributes' => array(
				'maxlenth' 	=> '10', 
				'pattern' 	=> '[0-9]{4}-(0[1-9]|1[012])-(0[1-9]|1[0-9]|2[0-9]|3[01])'
				),
			) )
		);

		WCVendors_Pro_Form_Helper::input( apply_filters( 'wcv_simple_auctions_end_date', array( 
			'post_id'			=> $post_id, 
			'id' 				=> '_auction_dates_to', 
			'label' 			=> __( 'To', 'wcvendors-pro-simple-auctions' ), 
			'class'				=> 'wcv-datepicker', 
			'placeholder'		=> __( 'To…', 'placeholder', 'wcvendors-pro-simple-auctions' ). ' YYYY-MM-DD ', 
			'wrapper_start' 	=> '',
			'wrapper_end' 		=> '', 
			'desc_tip'			=> true, 
			'custom_attributes' => array(
				'maxlenth' 		=> '10', 
				'pattern' 		=> '[0-9]{4}-(0[1-9]|1[012])-(0[1-9]|1[0-9]|2[0-9]|3[01])'
				),
			) )
		);

		echo '</div>'; 

I think I fixed it for those affected (Anyone who uses WooCommerce Simple Auctions Integration):

1)In class-wcv-simple-auctions.php, change wcv-datepicker to wcv-datetimepicker

This will not display the time picker, but…when you go select a date/time, the date will probably be improperly displayed as F Y , j or something like that.

2) Now you need to go to Settings -> General, and change your time format. Don’t try YY-MM-DD, as WordPress will display this as 1717-0404-0505 (rather than 17-04-05). You can fiddle around in the custom time settings, what worked for me was simply M-D

3) Now go back to class-wcv-simple-auctions.php and change the Placeholder to match your date format choice.