Went to a counter today.

The good news:
1) I wanted 12 items they had them all in stock
2) They can now tell you if they are out of stock at the time you
pay your money and you can order the out of stock items for collection
tomorrow. No more waiting for 15 minutes to collect to be then told
that they're out of stock.

The bad news:
1) If they are out of stock: they produce an order and you pay
for all that's in stock. You then wait for someone else to serve you
who produces a new order for the out of stock items to be collected
tomorrow.

They're getting there.