Unfair payment record

A couple of months back I changed banks and immediately informed Teljoy that I have changed banks and gave the new banking details, I received confirmation that it had been updated, so I relaxed, my debit orders then went of but didn’t notice that Teljoy didn’t debit on the new account even though I had received confirmation that my details had been updated, a few days later I received a call of no payment, I indeed went in to the app and confirmed that Teljoy didn’t debit, the person I spoke to informed me that my details weren’t updated, I then proceeded to make the payment manually and thought that was it, but Teljoy went ahead and marked that month as unpaid , which has since affected my credit worthiness as it reflects that I didn’t pay for that month, I am in the process of trying to obtain a vehicle and this is costing me now as it makes it seem I’m a bad payer, since having a contract with you I have never misses a single payment, besides that month and the payment wasn’t missed it was late due to my account not being debited, may you kindly correct this and remove that listing from my record . I never missed a payment but was a bit late due to the reasons stated above