how can someone be able to end the auction before the given time. Not one item but many.

[curraone]

the item/s belong to the seller until they are sold -

http://pages.ebay.com.au/help/sell/end_early.html

You can end your listing before the scheduled date. If there are bids on your item, you can cancel them.

Reasons for ending listings early include:

• The item is no longer available for sale.
• There was an error in the starting price or reserve amount.
• There was an error in the listing.
• The item was lost or broken.

[artyandchic]

Something may have happened ie.illness etc and they are not available to process sales.  It is just like a store closing the doors due to a number of reasons.