Insufficient Credit, but I shouldn't need them

[amazonlily]

Hi. I want to unlock my Sierra Wireless AirCard 880U (which apparently according to another post I found has an internal MC8780 something in it).
According to this page http://www.dc-unlocker.com/buy/dongle_price I shouldn't need credits to unlock either the 880U or the MC8780, but I bought 5 credits anyway to get a username and password assigned, but when I try to unlock, I'm told I have insufficient credits. I'm happy to purchase the correct amount, but don't know how many I need.
Can anyone help me with this?

[Vincentas]

Free unlimited is only if you have dc-unlocker dongle – a hardware key to dc-unlocker software. If you do not have this key, then you need to buy credits. You have checked the price list that is for dc-unlocker dongle users. There is other list for other users. You can find list here: http://www.dc-unlocker.com/buy/user_prices