I just bought 2 EP25P2 (v2.6) and I have an option for "billing" where I can enter how much each kwh cost and it adds the running cost for me.  I love it. I went out and bought 4 more but when I received them they were model EP25P4 (v1.6).   The P4 variant shows power consumption but does Not have an option to calculate cost.

Why is there a difference. I can't even find the EP25P2 on your support site to compare. How can I add that funcatality to the P4 version.