Is there a way to use vlookup to produce an instance result from two columns of info

hi john dalton. are you still using Excel 2003 like your profile says? your file is in xlsx. it's important for us to know, in order to give shorter & more efficient formulas. i have no idea what you need in column C of "outcome" sheet. i'm guessing the date if the client did not attend for 2nd time. for Excel 2007 & above, you can use:

Formula:

=IFERROR(INDEX(data!$C$3:$C$15,SMALL(IF(data!$A$3:$A$15=$A5,IF(data!$B$3:$B$15="Did not attend",ROW(data!$C$3:$C$15)-ROW(data!$C$3)+1)),COLUMNS($B5:B5))),"")

if it only appears once, you may consider:
=IFERROR(INDEX(data!$C$3:$C$15,MATCH($A5&"Did not attend",data!$A$3:$A$15&data!$B$3:$B$15,0)),"")

or:
=SUMIFS(data!$C$3:$C$15,data!$A$3:$A$15,$A5,data!$B$3:$B$15,"Did not attend")

the 1st 2 formulas are array formulas...confirmed by pressing CTRL-SHIFT-ENTER to activate the array. You will know the array is active when you see curly braces { } appear around your formula. If you do not CTRL-SHIFT-ENTER you will get an error or a clearly incorrect answer. Press F2 on that cell and try again.

you can hide the zeros for the 3rd formula by selecting the cells, right-click -> Format cells -> Custom:
d/m/yyyy;;
just add two semi-colons to whatever format you have

in Excel 2003 & below:
=SUMPRODUCT(data!$C$3:$C$15,(data!$A$3:$A$15=$A5)*(data!$B$3:$B$15="Did not attend"))