In my experience, a multithreaded browser doesn't help. Where a single thread would download at, say, 35kb/s, a multithreaded one would just split the bandwidth into 5kb/s // 5kb/s // etc...
BTW, If you have the pirate version of IDM, then it also turns the multithread into one and limits the resume capability

D)
On the comments in
Facebook I see a lot of official replies deflecting blame from MWEB onto Telkom, time of the day, browser, and even router - which is disappointing. Honesty really is the best policy.