Exorbitant charges

We submit our own electricity readings and have been doing so for some time as the guys have a hard time entering our premises. My mom used to wtrite down their number, they not digital so sometimes had a hard time and of course had issues or made mistakes. The time in question was since updated but we received a bill for over 9k for 2 months now I know for a fact that this is incorrect however after both my mom and I sending the corrected info they have not changed the amount and we need something to be done about this immediatly. I have since sent the latest and corrected info to them but still they keep sending the amount of 9k!! 9K is more than 6-9 months usage as its a single standing home! Please look into this with utmost importance. My mom has since passed away so its now falling to me to look into this.