Vodacom statement issues. Shockingly bad communication

I paid R800 eft on 1st February this year but keep getting a statement and threatening calls to put my line off. They say I owe R780. I reveived a statement showing the payment of R800, with a R0 owing, then the next statement the payment did not show. It is eft! Oh, and they deducted R20 from my account. No amount of emails or phone calls to vodacom sees this matter resolved. They dont even respond to emails. In store they say they will escalate the matter. I have even queried on social media but I don't get a response. In the interim I have received an ungraded handset, which makes no sense as they say they can't upgrade your phone if your account is in arrears. Hoping someone from vodacom finally fixes their mess.