Adding to accounts

I have upgraded my phone in July 2015 to a Samsung and from time to time I keep getting billed for BIS that I did not ask for. I upgraded another phone to an I-Phone in August 2015 and the same thing happens. On another number where I migrated in February 2016 I am also now being charged BIS while I have a Samsung. I also bought a LTE modem for R289 per month but my account shows R430. I have complained and sent numerous emails, visited stores and tried everywhere to get help but nothing happens. I am also struggling with their user-unfriendly statements that is sent via email. With limited date its download and download and download to look at the statements where in the past it was a normal word document. My credit limit is also being changed without my approval and some months my phones are blocked because I have reached my limit but a few days later when I receive my account it is less than my limit. This means that I was wrongly blocked but have to live with the discomfort.