Where can I buy a male Winterberry Holly plant?

I purchased Winterberry plants from B&Q a few years ago, and they were all female. Where can I purchase a male Winterberry plant? Does it have to be of the same species, or can a different Ilex male species suffice to cross-pollinate them?

The Winterberry plant you have is Ilex verticillata. It is next to impossible to buy male plants, and it is irresponsible to sell female plants and suggest that they might re-fruit. Moreover, this species is unreliable for fruiting in our low-sunshine summers, even if a male plant is available. In theory, other species might pollinate this one, but there are issues of timing and compatibility. Therefore, it is best to stick with the same species when looking for a male Winterberry plant.