No, they usually don't sell replacement parts for such sets - for several reasons.
One of the biggest problems would be that the costs required would be almost the same as purchasing a new set - they would need storage for packages of single replacement parts (which adds storage, accounting and production costs), plus the shipping and packaging costs, plus the helpline/service overhead to handle those replacement parts....
Usually you get the entire set replaced on warranty (and have to send in the entire set even if only part was broken), simply because it's cheaper for the companies to replace sets than to handle spare parts for low-cost-items.