Using Index/Match (Equal or less than) with Multiple Criteria

Hello everyone,

I've managed to solve most of this but I am now stuck on the final part and can't seem to find anyway to solve this.

I've attached a sample spreadsheet showing exactly what I'm trying to do and what isn't working here:
Padal_Excel_Lookup_Test.xlsx

Basically I have list of items categorized under a Main Category and Sub Category. The user selects the Main Category from a drop-down list, types a number for the Sub Category and using Index/Match lookup I then display some info about their selected item.

The array formula I'm using to do the lookup at the moment (which half works) is:

={Index(C2:C16, MATCH(F2&F3, A2:A16&B2:B16,0))}

Now if the user selects a category and enters a sub-category number that exists the formula works fine.

The problem is when a user types in a number for Sub-Category... if that Sub Category number doesn't exist then I get a N/A# error. Instead the lookup formula needs to return the row number of the next lowest number for that Main Category.

For example if you have a look at the spreadsheet I attached... you'll see that if the user selects Main Category BEF and Sub Category number 5, this combination does exist and so the formula will return Row 8 (so the info from C8 will be displayed).

On the other hand if the user selects Main Category BEF and Sub Category 8, this doesn't exist so the formula needs to find the next lowest number that does exist (in this case it's number 5) and return Row 8 like above.

So I tried to fix this by changing the MATCH formula to -1 but now the formula always returns N/A# even tho I've entered it correctly as an array formula. So I'm now totally stuck with this and was hoping someone could please help me figure out where I'm going wrong or let me know how I can do this?

Thanks in advance for any help you can give me.