Account

I had contracts at vodacom,I paid my last one at the end of January 2024 and gave them 30 days notice,as of this week they tell me I owe R690+ but it apparently is only showing on their system,on my app and on systems in the stores there is no proof showing that this amount is owed,it showes a zero balance,how is this possible?Wouldn't a outstanding balance show on all systems/apps etc,have been up and down calling then and between stores all they tell me is to pay the money but this amount is not justifiable and there has been no communication with me from any consultant of this,if I had not gone to the store I would not have known this.My account is now on prelegal on their system and they refuse to clear my name/change the status.On email and on my app it shows account is paid in full but they insist I owe them money but cannot tell me why.The staff in the bluff stores have been very helpful and even they cannot get answers as they have been restricted to check my account.They are ******.