Data billing Madness

I've been a client of Nashua mobile for about 8 years, they recently closed the telecommunication side of their business. So vodacom clients went to vodacom and Cell C clients to Altech Autopage. My subscription at Nashua mobile for the past 20 months for that contract is R399.00 per month. Now I get billed by Altech more than a R1100 per month for exactly the same contract, my contract was never locked, I never go over 2 GB. I've never paid that at Nashua, Altech says their billing structure is different??? I've phone numourous times and send all my statements to Altech for them to see that I've never been billed like this, ..... and response none, do they care... ZERO. Ashlee Jurakan is not getting back to me?