#2656 Edit service code on an existing invoice: fee doesn't change

[Hagir]

Process:
Create an invoice and submit it.
On billing History, click edit and change the service code on that invoice. Hit search beside it to ensure it's an existing code.

Expected:
When code updates, the fee should also update to a new value of the new code.

Current behavior:
Fee remains the same as the old fee for the old code and it has to be adjusted manually by typing

Tested on deb 146

[SBek]

Replicated in both Master and R12_1.