Guarantees are fairly pointless anyway. This is because they are usually given by manufacturers but your legal rights, in the event of a problem arising, require the retailer to put matters right.
Let's suppose that you buy an electrical item, made by Super Electric Ltd, from a retailer called Fast Sales Ltd. The item will probably come with a one year guarantee from Super Electric. You might as well throw this straight in the bin.
If it doesn't work as soon as you get it (or within a reasonable period theafter) you can demand a full refund from Fast Sales.
If it goes wrong within the first year, you should not claim under Super Electric's guarantee but go back to Fast Sales and demand a repair or replacement. (This is your legal right under trading standards legislation).
If it goes wrong in the second year (when the guarantee has expired) what should you do? No problem, you just go back to Fast Sales and demand a repair or replacemt. This is because European regulations state that all electrical items should be expected to work for an absolute minimum of 2 years.
What about after the 2 year period? Now we're into a grey area but a Uk court has recently ruled that certain items of computer equipment should be expected to last for a minimum of 6 years. This means that, for relevant items, you've got 6 years during which you can return to Fast Sales and demand the repair or replacement of a faulty item.
Manufacturer's guarantees are utterly pointless except in one particular situation. If the retailer has gone bust, then at least you've got someone else who can put things right (but only as long as the guarantee lasts. The 2 year or 6 year periods won't apply to the manufacturer). It's for this reason, and this reason alone, that I don't actually recommend throwing the guarantee in the bin.
Chris