I have a 16 year old 18 in high mortared limestone flower bed wall that has developed a crack along a mortar line. Apparently one side has settled a bit over time. I want to fill the crack with new mortar mostly for cosmetic reasons - hoping that it won't recrack any time soon.

Should I

1) Chip out mortar and replace with new mortar hoping to match color

2) Stain this mortar as seen on this website? instantmortarmatch.com

3) Pound old mortar to sand and mix or embed into
a) latex based mortar that will have some flexibility
or
b) epoxy mortar/putty

I don't really know how long the crack has been there so I don't know if it is stable.

Thx for your help
David - Dallas

Sorry, I can't seem to get my small jpeg of the wall to upload