There are a couple of threads below that cover a similar subject, you may wish to add your vote.
There are a few ways of tackling this problem so if we can get some consensus on what would work for the broadest number of users, we’ll explore that further.
http://community.quickfile.co.uk/t/client-credit-limits/4881
http://community.quickfile.co.uk/t/customers-on-stop-flag/5432