Aha! I think I see the issue. You are retrieving the value of the input field. Since this is “auto-complete”, all you did was type two or three (or whatever) number of characters to get the dropdown list. However, the input field only has those two characters - and, that’s exactly what you are retrieving and saving.
What you want to do is to save the text value of the item in the dropdown repeater that you clicked on.