Index-Match function with multiple criteria

So I'm trying to create an index/match function that will input data into one sheet referencing the data in another. I want it to input the offer number into the PO sheet for the Purchase order it matches according to: Customer name,Product type, and project $ amount. The offer number should be inputted in the "Offer #" column. For some reason my index/match formula is returning with a "too many arguments" error. The way I understand the index function and the formula I have been trying is:

=INDEX(Offers!B2:D24,match(Pos!B2,Offers!B2:B24,0,match(Pos!C2,Offers!C2:C24,0,match(Pos!D2,Offers!D2:D24,0),1

I'm sure theres something wrong with the way I'm setting this up but I honestly have no idea what that could be since I've been trying everything. Any help would be greatly appreciated.
I'll upload a sample file to show what I'm talking about.