Still getting debit after phone has been cancelled

My phone *** was cancelled on the 18th february 2015. I received confirmation that it would take a month to cancel - reference ***A - I spoke to Florence. I received an account in April and phoned again with same reference no and spoke to Julie. She confirmed it would be sorted out as I had received notification that R341.76 would be taken off for April, even though i did not have the phone anymore!!!. She confirmed that the last account i would receive would now show that the last time i used the phone was 8th March 2015 - but then on 28th April the amount of R341.76 was taken off my account. Please reverse this amount urgently - the process of cancellation was done correctly and you will have my phone calls as reference as well. Please confirm that this money will be redeposited and also that the account IS CANCELLED as per the phone calls and reference no's provided.