Getting Billed after Cancellation

On 01 April 2015, I requested a cancellation for my services due to us relocating. Ref nr.: ***A***5. So on 10May2015 I received an invoice for May usage of R907.05 (R587.13 arrears, which I Understand, but the R319.95 I Dont) (note that in May I were not staying there anymore). On 12June2015 I received another invoice for R370.05. This Time I called and it was explained to me that it will be the last one, because I pay for n month in advance because I cancelled my subscription?????? So I paid it. So on 9Jul2015 I got ANOTHER invoice, but this time for an amount of R 826.26(note my subscription was R587.13). Now please explain to me *** is going on? are you busy MILKING the customers cause you are in financial trouble? I HAVE NOT USED ANY DATA OR MADE ANY CALLS FROM THAT ACCOUNT SINCE 28 APRIL 2015. So why do i keep on getting invoices? The invoices even states usages... FOR WHAT? Did u reactivate the service for new tenants of that house, now you are charging me? Get yourself together and rectify your S...T please. You are a leading company in this land, how can you let this happen. You making a bad name for yourselves.