Slow Speed - only 300KB/s with Dropbox

I have a 500MB/250MB fiber line with Webafrica. International speed is limited at 10MB only. If I download from Dropbox I get only 300KB/s. I have support tickets but never gets a reply from them. I paid many months a premium service price for slow speeds. This service is far worse than an old 3G connection. I will soon move to a new provider.