Overbilling

I am being over billed on my account with Teljoy. On 16th August 2017 they approved and delivered my unit ***5. From my experience in the past with them I know that you need to make 37th payments to them, 1 payment is for the prorate for the unit received before month end. That means that they will debit amount your account 37th times, 36th full payments and 1 for the days your received the unit. I am trying to explain to them that they cannot charge me for October 2020 for the unit but they still keep saying I need to pay for the month of October 2020. Unit received 16th August 2017 – 1st Full payment they debited on the 1st September 2017 therefore if you calculate 36 full payments it’s until 1st August 2020 and then the 37th payment should be the 1st September 2020 but not the full amount only for the days from the 16th August 2017 – 31st August 2017. But I paid the full amount and did not complain. I only notice that my account is in error when a credit check was done, now that I am trying to rectify my account they still inform me that they need a full monthly payment on the unit for the month of October 2020 but I know very well that 37th full payments to that unit was made. Now to clear your name or to get a clear credit you must just made the payment otherwise your credit score won’t change. Really we are the fairness as a client.