Backup issues

HI Guys

I'm having issues with a few sites that just refuse to backup – Clients are paying for the service, but it's not backing up at all.

I am successfully getting Snapshots, but can't get your Automated backup to work properly.

It does seem to be only on the slightly larger sites (90MB+).

I use a shared server for most of my clients and I'm aware it could just be the server being slow at the time the backup is attempted, but I was wondering if there's anything I can do / settings I can change to increase the chances of a successful backup each week.

I'm on-selling these services at a well priced rate, but having so many failures with the backups means I'm actually doing more work than if I backed up manually once a week