Have to keep formatting micro sd card

hello,
I've been using this sandisk 8gb micro SD card since the past 1 year but I'm getting sick of it. everything was all okay for the first 6 months but then it started renaming all the files & folders with the greek letter 'mu' which looks something like a 'u'. then it became write-protected and showed a total size of 106gb files in it which is impossible.

I copied as much data as I could to my pc but the rest was lost. I formatted the card and it became usable again but the problem returned in a few weeks. So I repeated the process several times and once also did a factory reset to my phone yet the problem returned in 3 weeks. finally I bought another sandisk 16gb micro SD and the same thing happen to it. what is wrong with this? there's no virus on any of the devices because I've checked them a million times with different anti-virus programs. Please suggest a permanent solution to this, which doesn't involve formatting because it loses my data.

Some help would be appreciated. Thanks!