Get Data From Excel Pivot Table

Hi folks,

My source is a specific Excel pivot table exported automatically from MS Project visual reports. This pivot table have 2 hierarchical level in columns : Year and Month, as shown here. Unhappily enough, year takes a line, and month a second line.

When I import it into Power BI Desktop october release, I get columns, but years and months are still separated.

When I unpivot all months columns, I get a lot of "columnN" in the attribute column such as : 

What I did is to rename all columnN one by one with the corresponding month,

WHat i want is to get this (made with 10 replacements and a filter) :

How can I do to avoid manual renaming of columns and rename automatically columnN with MonthN (for instance Column6 = Janvier-2021)? I did it manually but this is not suited for repetitive use.