OVER 1000 Payment on time but I'm declined because of ONE late payment a year ago.

I have had a Vodacom account since 2009, during these 10 years I have had about TWENTY contracts which were all paid perfectly. In 2018 a ********** debit order went off my account and when Vodacom tried to debit my bank account there were insufficient funds. I then reversed the ********** debit order and paid Vodacom exactly what I needed to pay. So out of more than 1000 debit orders, there was one that was a week or two late. Now in 2019 August Vodacom will not let me upgrade my existing contracts because they say my credit score is the worst. From 1 missed debit order in 10 years. I have not missed any other account payments in my life. Just the one Vodacom payment in 2018 was a bit late. So now they don't want my money because of that one debit order that was late a YEAR ago. Vodacom is just a bunch of *********** people using systems they don't understand because if they knew what they were doing I would not have a "BAD" Vodacom Credit score. OVER 1000 payments on time, ONE payment a week or two late from a year ago and now I'm "JUNK"