Cancelled my account but still receiving bills

<p style="margin: 0cm; margin-bottom: .0001pt;"><span style="font-size: 10.0pt; font-family: 'Arial','sans-serif'; color: #555555;">To whom it may concern,</span></p> <p style="margin: 0cm 0cm 0.0001pt;"><span style="font-size: 10.0pt; font-family: 'Arial','sans-serif'; color: #222222;"><br /> <span style="border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;"><span>on the 31st of March I gave one month's notice to cancell my subscription with Telkom. I emailed all the do***ents they requested to </span></span></span><span style="font-size: 10.0pt; font-family: 'Arial','sans-serif'; color: #555555;"><a href="mailto:***" target="_blank"><span style="color: #1155cc; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;">***</span></a>. I confirmed the cancellation by calling and spoke to </span><span><span class="gd"><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;">Aaron Boaz Stallenberg who confirmed that one month's notice is sufficent.. </span></span><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;"><br /> <!-- [if !supportLineBreakNewLine]--><br /> <!--[endif]--></span></span></p> <p style="margin: 0cm 0cm 0.0001pt;"><span><span class="gd"><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;">After I had emailed the do***ents to telkom, i received an automated response entitled "</span><span class="gd"><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;">AutoReply : </span></span><span class="il"><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;">Telkom</span></span><span class="gd"><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;"> Service Cancellations"</span></span></span><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;"><br /> <br /> </span><span>Today I receive an invoice for May-June 2016. How is this possible?</span></span></p> <p style="margin: 0cm 0cm 0.0001pt;"> </p> <p style="margin: 0cm 0cm 0.0001pt;"><span><span style="font-size: 10pt; font-family: Arial, sans-serif; color: #222222; border: 1pt none windowtext; padding: 0cm; background-color: white; background-position: initial; background-repeat: initial;">Should I not receive any feedback from </span><span class="il">Telkom</span> in this matter within the next 24 hours, I will instruct my bank to block all payments requested by <span class="il">Telkom</span>. I have done my part and kept to the agreement.<br /> <br /> Regards,<br /> Mark</span></p>