Contact dispute 10 years later

I once had a cellphone contract with Telkom 2014 it ended 2016,I went to their store at Maponya Mall on 20/08/2025 for number porting to my suprise I was told they can't help because I owe them R2155+ I was puzzled 10 years later,I was advised to call customer care and log a dispute upon calling I was told they can't assist because it was month to month but how I was never advised to cancel my contract to my understanding if it was month to month and they couldn't debit why not make me their customer aware that there were no funds available what made me angry the most is that I paid every month after my contract ended I never used their sim card it is their duty to let their customers know that if you take a contract a month before it ends you need to cancel. I'm so angry with Telkom they didn't even try and make me aware of this 10 years passed if I never went to their store for number porting I wouldn't have known