For relatively simple problems we would often use the Redbus 'remote hands' from their on call engineer. If this is inside our contracted allowance we would not charge for it and otherwise we would pass on any charge at cost price.
For anything more technical or for which you'd prefer someone with a much greater depth of knowledge we have numerous contacts between 10 and 30 minutes from the datacentre available both during and outside office hours.
The transfer figure is in Bytes
I'll drop you a brief email now with a little more information.