Fee to access HD channels.
Subscription packages only include subscription to SD channels and you have to pay HD access fee to get HD channels. The number of HD channels you get for the fee is dependent on your base package, that is, if you have access to SD channel in the package you have subscribed you get the access the HD feed of that channel.
Therefore, in order to watch a HD channel you have to have its subscription in SD and you have pay HD access fee.