May I know the cost per unit (kilowatt) of electricity in Nigeria,

I just recharged my prepaid metre and I feel short-changed.
I paid 500 Naira and was credited as follows:
Units of electricity bought: 42.9.
Cost of electricity paid: N476.19.
VAT paid: N23.81
Total cash paid: N500.00
A little mathematics shows that if 42.9 units of elect cost N476.19, 1 unit (kw) of electricity will cost 476.19/42.9 = 11.1 (eleven naira, ten kobo only).

Now to my confusion, I was told that d cost of electricity was increased from N8.50k to N10.00 per kilo watt, how come I bought mine for N11.10k/kilo watt? Using N10.00/unit, N476.19 wud buy me 476.19/10 = 47.7 units, a difference of 4.7 units. That's like 3 days of electricity!!!

Is the PHCN unit more than the kilowatt? Who is extorting Nigerians? I truly need an explanation here.

In my compound where i recently move in,I.meet a prepaid meter of 560.92 kilowats, how much is it in naira to pay off the outstanding bill,someone should help and calculate pls.thanks.