Unlock required

You need to work with your S-ISP to have them unlock that box.  If they are using the lock feature, then they in fact know HOW to unlock it.  If you can prove ownership of the unit, you can work an angle thru iDirect TAC to have them provide you with a key to unlock it.

If you can prove ownership of that unit....Yes.

iDirect's official position is actually that the person shown in their records as having ownership of the unit must provide written permission for the unit to be unlocked. 
That means, whoever bought the remote from them, or, if notification of change of ownership has been provided, whoever that relates to.
iDirect, quite rightly in my view, do not get involved in disputes between ISP and end user, it's down to the legal obligations on either side of that agreement to prove ownership and to behave responsibly. 
If your ISP will not unlock the modem, you can always go to iDirect and request an unlock key, they have a record of the modem serial against who purchased it and will ask for permission from that company, without that, I would expect you to have a hard time getting an unlock key from them.  Think about it, if your provider won't unlock a modem for you, for whatever reason, iDirect are unlikely to unlock it as this is going against their own customer.  Not great business practice.