I went on-line and ordered a specific tool from Screwfix ... then thinking 'while I'm at it - and qualified for 'free' postage -I'll order up some 'spare' things, rawlplugs, fuses, screws etc". The order was accepted and an email received in confirmation. Feeling pleased with myself and told my wife 'Sorted!' and settled down with a cup of tea. The 'phone went and my wife turns to me with a 'It's Screwfix, there's a problem with your order ... !" ... Screwfix's young lady said, 'The _tool_ you've ordered .. it's out of stock and we don't know when it'll be back in stock. Do you want the rest of the order?" "Oh, bother!' (or words to that effect)"that's the only item I actually wanted, the rest is just make-weight to utilise the 'free' postage!" That's all right!" she said "We'll waive the postage and send off the remainder. Sorry to have inconvenienced you!". The package arrived the following morning, and my bank account confirms that I wasn't charged for the non-supplied tool. This is service of a very high level. Thanks, Screwfix.
I managed to obtain the required tool ... but at a higher price than from Screwfix. That's life, and desperation :(