Count Unique values based on criteria within 2 columns

I hope someone out there has the brains to help me with issue.

I have a spreadsheet that has multiple columns and duplicates. What i want to do is count all the unique values in column A, only if Column B and C equal unique text specified. I have outlined an example below:

Column A    Column B       Column C
24          Unit a          Type A
24          Unit a          Type A
26          Unit C          Type A
25          Unit A          TYpe A

So using the above as an example the end result if counting unique numbers in column A, that are in Unit A (Column B) and Type A(Column C) = 2.

Im pretty sure I need to utilised sum, frequency and match but have not been able to it to yeild the correct results.

Im using Excel 2010

Solution 1:

an easy hack to achieve this is to use Column D:

= Concatenate(Column B, "###", Column C)

then you can do CountIf(ColumnD = TheValue)