The cost of any testing work has to reflect the amount of time required to do the testing..
And the time taken will depend upon the complexity of the installation..
The type of cable used wouldn't generally have much of an impact?
However accessibility to the existing CU, accuracy of the circuit description labels, how neat the wiring is inside the CU, if any previous electrical certificates and/or inspection reports are available.. can all have a significant effect on how long it takes.
e.g.
A CU stuffed in the back of a kitchen cupboard where you have to work on your hands and knees.. -vs- above a doorway up on a stepladder.. -vs- at a nice eye-level height on a garage wall when standing on the floor with no clutter or obstacles in the way..,
A CU with no circuit labels or incorrect circuit labels -vs- a correctly labelled CU with previous inspection report or Installation certificate available..
A CU where the internal wiring is a rats-nest -vs- a very neat CU with all circuit conductors identified and cut to appropriate lengths and dressed correctly into their respective numbered terminals...
Any combination of the above could flip the balance between a really easy, quick and not to expensive job -vs- A pain in the bum, time consuming more expensive job!!!
A photo of your existing CU, and the incoming suppliers cut-out, and the meter...
may help us to give a bit more realistic estimation??