Mining rig (absurd electricity bill?!)

Hi, I don’t know who’s at fault here I remember when I had my two Antminers I had calculated the electricity expenses that miners would incur with the help of the calculator that the Electric company offered online with specific city pricing and they offered to calculate it as a business and as a residence so I did my duty and pre calculated any variant possible(time,city, hours per day, mining rig electricity demand)and came to the conclusion that the bill should not exceed a certain amount but apparently it costed waywaywayy more and it should have not!?

I never got to see the bill myself but what could have caused a surge if everything was publicly available so the calculation was easy but is the Electric company allowed to hide costs? Or could it be the Antminers electricity demand /usage that is shown on the papers of the product that is wrong?