Vodacom is a nightmare in my life

I wrote to hello Peter 3 weeks ago about my son's tablet that I got from vodacom contract over three years. This tablets started to give us problems from the second month of receipt. Vodacom refused to change it regardless of it being booked in 6 times for repairs. On Monday the 15th of May 2010 we collected it after repairs as my boy is struggling to study without text books as they are using e-learning at school. Sadly yesterday when he was studying it just froze again. I really don't know what to do as it will be going back for repairs for the 7th time while my son looses out on his work. Really is this how customers must be treated????????????????????????????????????????????????????????????