I’m on Vidahost too. I’m starting to see a pattern here…
It was Suliman who had me also. Out of curiosity, who is your hosting with?
I have completely deleted the databases and all files, fresh installed EVERYTHING and still have the same issue. They obviously have access to phpMyAdmin (even after changing all passwords) as they’re able to change the WordPress username. They also keep changing my cPanel password so it seems this is more of a server issue rather than WordPress/Database. Oddly though, they aren’t actually trying to get into the WordPress admin panel anymore…
I’ve tried a couple more things (md-5 encryption on passwords, more password changes and permission alterations) – If this doesn’t work I will be nagging my hosting provider to change server.
I’ll be sure to post as soon as I have a solid solution!
Having the exact same issue! – Please let me know if you find a solution