So I have a solution but it is not totally able to re save them on your phone,you will only be able to save them in a word file
1-convert the .bak (backup) file to into zip file by renaming it and changing the last word after the dot from .bak to .zip
2-unextract the zip file with winrar , open the folder and you should find contact.list file,leave it.
open a new document notepad , choose open and click on the "contact.list" file to open it in the notepad text
3-now select all and copy them into a word file,you can search for your numbers or specific contact by the search and replace tool of the microsoft word.