The small retaining wall and steps in this garden were build 2 years ago (not by me) with softwood sleepers, they have not lasted, they were also not installed properly, the rot was extensive and they were all thrown away.
I suggested we rebuilt using concrete blocks, render and matching pavers, and as you can see I sourced the same grey sandstone which in time will weather in to match the existing or the old pavers could be cleaned to match the new stuff. I also took the opportunity to raise the wall a fraction so the top area is slightly more level.