Still being billed yet my services were cancelled almost 3 months ago!

I cancelled my services at the beginning of May and I am still being invoices. The incompetence of this company was the only reason I left them, there services and network are very good... but you have endless problems with the ancient portal and systems and if you want to get support don't bother emailing them or using the whatsapp chat.... the only thing that has worked for me is to sit on the phone and wait in the queue. There is always very long queues too, so either they have lots of people signing up or lots of people having problems. PLEASE STAY AWAY, this will only annoy you for months too come.