As an accountant, we have had a couple of clients that have managed to post sales/purchase invoices to a bank code which has somehow caused the trial balance to not balance.

I don't claim to be the smartest person, but surely if the software is doing something that causes something named 'Balance' not to balance, something is wrong.

Other software providers do not allow such an issue to arise, Sage One for example has an error message that pops up saying this cannot be done. If other software providers are not allowing this to occur why is it that Kashflow allows this to happen.

Can you please amend the software so that bank accounts cannot have invoices posted to them! In the long run, this will save you, your clients and the accountants that push client to use software packages a lot of time and effort!