Provider uplink testing

Dear All,

I am in a problem with a provider who is unable to meet my demands interms of uplink capacity.  I did request for an link with parameters 64tx/64rx 1:1 contention because I am doing some voip and was allocated. On running bandwidth tests using WIMI, I get an uplink averaging 45kbps and a downlink of 127kbps which makes me doubt the link.  What surprises me is that the uplink never pases the 45 mark and sometimes drops down to 25 and keeps on fluctuating throughout where the downlink which I do not need bursts upto 138kbps.  Are this guys cheating me?  Are there any other tests that can ascertain my link parameters?

Malachy