How much to call 0844 numbers??

[#1]

It seems virtually impossible to work out how much 0844 numbers cost to call?
Asking Jess [!!!!??] is NOT helpful. [Is it EVER helpful - a complete waste of time. and there is no e-mail address for Customer Enquiries!!]
Why on earth doesn't Plusnet show these on their tariff page?
Less than impressed.

[#2]

Unfortunately BT (Wholesale) have several (many) chargebands for 0844 numbers so Plusnet charge acording to what they're charged by BTw - see http://community.plus.net/forum/index.php/topic,115999.msg1001086.html#msg1001086
Then refer to https://portal.plus.net/home-broadband/tariffs/ (look in section 'Specialised Number Call Tariff') for the call costs.