ABSOLUTELY do NOT call client B back to discuss money! That is none of their business. You are hired by Agency A – you only respond to them. Ethics go a long way these days. You should CALL, not email, Agency A and let them know that you were contacted outside of the scope of your production responsibilities and want to remain in good standing with them. Why lose 2 clients. You can inform Client B that it is not your place to discuss costs as you are not their direct vendor and they should contact the Agency A if they have pricing concerns.
If either A or B balk at their relationship with each other, you still come out ahead! You’ve kept peace with A, who should still call you, and peace with B who will come back to you directly. now you can discuss costs, not to mention you are in a better position to act as a 2 roles for them, agency and production.
Steve

