unauthorised debit and no refund

I cancelled my contact which expired on 28/2 by providing Vodacom with notice in December 2017. Even after following your rules my account was still debited in March 2018 and April 2018 for my subscription. I called in on 4/4/18 and spoke to Zanele who confirmed that the debits did go off in error and that she will log for the refund to be done to the value of R1496.98 which was the two months (R748.49 X2) ref no: 1- ********** ********** 0 and I was informed the refund will take 7-10 working days. I waited patiently considering the public holidays and on Saturday I called to follow up to be told by a lady that the reversal was done however the refund was not requested. She assured me that she will escalate it even asked for my banking details, ref no: 1- ********** ********** . this morning I call in and was told that she escalated it to the wrong dept and this amount was now just pushed to my other contract which is a top up account that I have for the kids. this is not what I asked for? so I asked to speak to a manager, Phindile came onto the line and he called me after assuring me he will resolve this, at 07h39 (ref no: 1- ********** ********** ) he informed that "they" have decided I will now only be refunded R390? so I asked to speak to them as I need to understand how this was decided, I was told no I cant? so this is apparently and offset to my bill, ok so who authorized this and what happened to the rest of my money? I am lost here - you Vodacom debit my account without authorization on a cancelled contract and then you make me call you for follow ups with 1hr plus conversations at my own cost to mess me around? Can someone with authority please look into this and get back to me with a resolution as I am the one that is now inconvenienced and my rights are infringed upon.