You can't possibly be asked to pay something extra when the feature is already there but it's broken. Backing up a data file is no joke and I'm sure you're aware of it. I have multiple clients and I have set up automated local backups but from time to time it creates a temp file and it's a HUGE RISK.
And in this case I'm not alone. Countless of other QBDT users must be facing the same looking at the threads online. Why don't you provide a real permanent solution to this matter instead of asking to buy subscriptions?
