I payed double because of your employee mistake

on the 5th of May I upgrade from 4G to 5G, I ask the lady that was helping to cancel the 4G as it will never be used as i have the 5G internet now.

My bill on the 1st of June was too much due to the person that didn't follow the correct instruction, i want my money back for the 4G deduction for the 1st of June 2021