My Dad Wanna Sue BEDC[NEPA] Due To Estimated Bills For 2yrs Now

SO guys this last bill nepa brought ,they gave us 34k as bill. For the past 2-3yrs nepa have been using estimated bill on us, when my dad noticed it he went to complain their office here in ughelli[delta state] where they told him to pay what he use to pay that is their fault...From then the bill started pilling due to estimated bill . Last week when the bill was brought they wrote pay 45k to aviod disconnection,,, my dad immediately called their marketer and we snapped the reading of our meter to him... he said what the meter is reading is different from what is in their system.. he said the problem started may 2020.. he told my dad cant do anything that he should take the meter to their headquater.My dad is now considering suing them...guys your advice is needed pls... i dont mind if this go to front page.