Multiple Dependent Data Validation drop down boxes

Hi, I have read many links here and on other sites that say how to do B dependent on A, and C dependent on B. I'm trying to make both B and C dependent on A.
I have attached a very basic sheet. In it I have A= account names. B=Corporate customer contacts, C= Cities they have offices in
Right now if I choose from a dropdown in A the company name, in B I only get the contacts names that work for that company. That part works fine. In my formula area on the right side of the sheet I have an additional area that lists the company names again (that is the "foundation" info) and this time next to it is the cities. How can i make column C offer me the cities based on column A while still having column B function as it does? I hope this makes sense, please see the attached.

See attachment:

Thank you, if I can ask you one more question please. I see that in my column C the data validation is =INDIRECT(A5&"C"). What I can't figure out is how you tied it to the cells 16 - 18 M-P. I first thought it was how I did it in the section I have for account names and contact names. I high lighted that area and then held down CRTL & Shift while pressing F3. It came back asking if I want to replace the current definition of "ford" so i know that my guess was not correct.
So i guess my question is I can add the =INDIRECT(A5&"C") to the column C but not shure what I have to do to that row of cities in my formula area to have it look at it.

I simply selected N16:P16 and named it "FordC" (via the Name Box), then selected N17:P17 and named it "PepsiC", etc...

got it, thank you so much