I strongly suspect the problem is not in your machine at all, but in the machine(s) that you use in the internet cafes.
Whilst I am happy to assume that you look after machine and floppies reasonably carefully, we can make no such assumptions about the cafe machines. In particular, other users of those machines may bring in a floppy that has been in their pockets for days, or lying around in the dust of a car or whatever (depends on which part of Africa you are in!) and then the dust or muck gets transferred onto the floppy drive heads and mechanism, ready to do damage to your floppy later on.
Just as a matter of interest, when you have put your data onto the floppy in the cafe, have you ever tried to read it back before you bring the disc home?