WORST customer service EVER

I was a Nashua Mobile customer, and when they closed down last year my Cell C contract was moved to Altech Autopage. I've been trying to get Autopage to debit my bank account each month since February. I've spoken to customer service on 18 February 2015 - the lady I spoke to said they had my banking details. In March my phone got cut off - after I paid the amount due. Went to the shop in Canal Walk where the assistant changed my payment details on the system. In April my phone was cut off AGAIN, so I went to the shop in Three Rivers, Vereeniging, AGAIN and changed my payment details on the system. On 15 May 2015 my phone was cut off AGAIN. How many times on how many different ways should I try and get Altech to use a debit order for the amount I owe them?! And all this without receiving any statements since December 2014. They do have my address - I received 1 statement from them in December. I never know how much I am supposed to pay - until I receive the SMS ( twice now AFTER my phone was already cut off) saying I have to pay immediately to avoid suspension of services. I'm so fed up with this appalling service!