Unfair invoicing

I canceled airtime upgrade and a cellphone contract but I was invoiced on both when I was invoiced for my other two contracts with them and now they have blocked my account because I reversed the debit order, they say my account is in arrears. I visited the vodacom shop at Dihlabeng Mall to address this matter but I was told by the franchise manager that they cannot help me, I must call their call center which failed to assist me with correctinvoicing and cancellation, saying they need confirmation from the store.