Without knowing the nature of your relationship with the retailer you spoke to, I can think of these off the top of my head.
1. The retailer was mistaken/misinterpreted the information they received from Hornby.
2. The information from Hornby was correct at the time, but the policy had changed either before or was changed after that, meaning that both are right: i.e. different information was given to different retailers at different times.
3. Your retailer might simply not want to stock any of the range for commercial reasons best known to themselves, but do not see the need to elaborate on that to a customer.
Plenty of others I'm sure.