Vodacom
BIS download are very slow after 3 months

I've upgraded to BlackBerry on my prepaid SIM card recently, mainly due to VodaCom's (then) great BlackBerry InterNet Service deal.
My first BB was an 8520, I've switched to a 9360 about 4-5 months ago.
Recently I noticed that when downloading content (mainly documents and music) that my BB 9360's download speed has crashed from up to 130KB/s, to about 6.5KB/s.
According to the BB manual and the phone's online Help tutorial, one can download several items at once, but with my phone's current download speed, when I download a second item the download on my first item Errors, and my Browser is excessivly slow, even if I don't have Tabs open.
I then joined a Forum on the [URL Removed] website, and there read several queries from VodaCom prepaid and Contract clients alike, complaining about the same thing.
The response to these queries was, that it is not the phone, but the Service Provider, or Carrier, that is responsible for the crashing download speeds.
My question is thus the following: Why aren't consumers informed upon purchase, that the dowload speed will falter after a few months of use, and that there is (to my limited Google research) no known fix for this?

Company: Vodacom
Country: South Africa
City: Pretoria

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