Additional Charges vs Quote

I recently sent a package from Cape Town to JHB. Online the estimate was around R315 as quoted per 9kg weight, which was a little more than providers. I opted to use them. By my surprise I an additional R670 the next day, once package was collected. Turns out they charged me for 67kg volumetric weight instead of the 9kg that the package actually weighs. They take the greater of the two, which is not clearly stated on thier quotes.