Sell a product but not the blades for it? useless

Builders Warehouse, both Alberton (New Market) and the Glen stock Garden Master Bow saws and extendible saws. Both stores however do not stock the blades for these products. their shelves are lined and packed with lasher blades, but i bought the garden master products because their handles are not steel and do not cause blisters as easily. now i'm stuck with a product they do not supply after sales parts for, why stock the items in the first place? i was in builders Alberton and they phoned the Glen branch and told me they had stock of the Garden Master blades. i drove from garthdale to the Glen (40km's) to get a few blades, and surprise, surprise, they tell me they're out of stock.

I go to builders at least once a month, and have NEVER seen any garden master blades for the saws i've mentioned, so why the hell do they even bother selling a product they don't supply replacement blades for?