It's supply and demand in action. Each oil company has limited capacity of production and not much flexibility to increase it in short term. As part of the supply is no longer available, there is less oil available in the market. The market mechanism drives the price up to a level where supply and demand are in balance. So the migration of oil consumers to alternatives is exactly what's supposed to happen in this case.
Moreover, a single company does not have a real choice to sell for cheap. First everyone would choose this vendor for their oil needs. But as their stock and production is limited, they would soon run out of oil to sell. Even a cartel or government decision to lower the price does not cut it, because it kills the demand side incentive to find alternatives. Then you'd be in a situation where oil is cheap, but not available.