All backups are deleted from my FTP account

I need to cover all my bases here.

Im using BackWPup on about 20 different, all up to date, wordpress sites and the backups get saved to an FTP account of mine with a certain hosting company. BackWPup has worked for me for years, until this year. A few months ago i noticed ALL my backups for every website was deleted, gone, nothing there (thats 40-50 compressed backup files, plus the folders for each website, plus the ftp folder itself). I contacted my web host and they claim it wasn’t them who did it. Although mad, I worked on getting new backups for all my websites using BackWPup and they’ve been backing up well the past few months. Today I check on them and notice they’re all deleted AGAIN. I rarely ever get into the FTP account. I just set backwpup to backup there and forget about it. No one else and no other ftp client has access this ftp account.

Im not saying its an issue BackWPup but id like to pass this info along cause my host claims its not an issue with them. Any help is appreciated.