Debit order on cancelled contract???

I had a contract with Vodacom which ended in April, I called in Feb to inform Vodacom that I will not be renewing my contract and was advised to call in March to cancel the contract since it expires in April. I did as I was told and called again in March to cancel the contract, and was told that my cancellation is successful and was assured by the accounts dep that my last debit will be 1st April and that my sim will be converted to pre-paid, I then received an sms tht my sim card migration request has been processed on the 30 April 2016 since my contract has ended. So basically the last invoice and statement I received was in March for April and no statement received In April. My debits go out on the 1st and incase of a holiday they usually go out the next day. With my surprise I received an sms today 4May 2016 informing me that Vodacom has debited money from my account???? I called the call center and I got transferred to contract dep, from there I was then transfered again to accounts department coz both agents couldn't help me since my number is now pre-paid. Finally I got to speak with an agent from acc dep and told her my story, she tried to check as well on her side what was happening but she couldn't also confirm on her side then decided to put me on hold while she speaks to her Manager. She then came back to me after she spoke to her manager and was advised to tell me that the debit that went through this Month was for April of which doesn't make sense since the March invoice stated that the debit order for April was gonna go through on the first of April of which it did. So my question is why am I paying for May and why haven't I received the statement for May if that's the case??? and how can the two previous agents I had spoken to, confirm that April was my last debit if it isn't so??? Why was the money debited on the 4th???? in 24 months of my contract with Vodacom that has never happened and lastly where is the airtime and data that goes along with that money you just debited coz I haven't received any? I'm really dissapointed with Vodacom's service and no longer want anything to do with this company in future, they are ***** and will come up with any excuses not to give back your money. I wouldn't advise anyone to take up a contract with them, coz cancelling these stupid contracts is a nightmare. They dont even send a confirmation for cancellation so that they can cook up more stories as to why they have to keep taking money from your account. I just want my money back!!