not trustworthy, irregular practise and no support

I am a longstanding customer of Autopage, probably 15 years. I bought an i-phone for my son and late last year received a shocking statement. The account was R2000 more than normal. After discussing this with the owner at Autopage Sunridge, they assisted me by capping his usage up to R50. Further to this i also signed a document confirming it will never exceed R200 ever. My Mat debit order went off and yet again R1600 on my sons account. After meeting with the owner they said they will escalate, came back and said i am liable for the R1600. So firstly, why did they set the system on R50 capping, why let me sign a form to ensure the amount will NEVER exceed R200 and then tell me there is no guarantee.i am about to take out two new contract phones as well as tablet, but am ery disapponinted in the bad customer service,after sale service and general feedback? Please contact me *** wayne tait