There are two vendors working for the same client in different departments
One of them, let us call them 'A', looks into the global IT operations, improvements and projects. The other one, 'B', provides warehousing and distribution services. 'B' uses IT services provided by a third vendor, 'C'.
There was an issue in the IT solutions used by 'B' and this eventually was reported when it's consequence reached 'A'.
Now, should the client, who is a customer to both 'A' and 'B', let people at 'A' communicate directly with people at 'C'? What if there is a cost raised by 'C' as a result of this communication?
I know this isn't an every day concern to many, but from an audit standpoint, if I am a vendor and so is my friend, I could charge my client a lot more by introducing issues that are of little importance.
My question is what should be the ideal approach in this case?