Optus wireless modum internet speed problem. from 3.6MB/s to 10kb/s. please help?

[lordunforgiven]

I got a new wireless optus modum the ones that run on the hpone sim card. and about 2 weeks ago it suddenly slowed right down. im still connected at 3.6MB/s and have 4.5GB left of download but when im downloading programms it download between 15KB/s - 1KB/s.
And loading a simple web page like this one which normally is done in less than ten sec. takes 5-10 min.

Does anyone have any ideas, i reall need my speed back.

cheers