If there were also Interactions for this Source, then the correct step would be to send it to MS Tech.  In this example, there are no Interactions.
 
To fix the issue:

1.  The client has to change the Campaign on the Source record, which can be done front end in Source Code Entry,
2.  Then they can do a CAB on any Transactions using Source AHQWD18NTAA001 and then
3.  Click the “Sources” button on the Batch Summary screen of the resulting batches to recalc the source.

That should bring in the corrected campaign value. They should make sure to check the Batch Detail items to make sure they are now reflecting the corrected Campaign before posting the batch.