I did that, and no change.
However, I fixed the problem. For some reason the "CentOS" repositories were not enabled as they are supposed to.
After enabling them I found the "lost" updates! Simple solution, but not obvious...
The problem with non-working mirrors were still there though. It seems as though I fixed that as well, by searching this forum. I was in a haste, so I cannot post the exact solution , but I found it under "upgrade to 7.2" in the wiki.
/Salmoneus