Not delivering the product promised

About four months back I was about to move house and I did not have any telkom phone lines in the area so I was looking for a wireless solution. I found Neotel and Bitco and opted for Neotel due to some great upfront service. My understanding from the emails between a sales guy from Neotel is that I will be able to upgrade to a 10mb wireless package and confirmed this when they installed with a test of just over 9.2mb. Now after upgrading I am not getting anywhere close to that speed and I'm paying R1799 a month and I'm only getting around 5mb. I spent almost 30min of my free cell phone contract minutes trying to sort this out but I'm getting nowhere and Neotel will not even call me back. I have also noticed during the evenings my speed drops to around 3mb, I think Neotel has overloaded a tower and in terms over selling a service.