I had much the same problem some months back. Group of developers felt they were above the rules and were fiddling on Prod using a SQL account for a messaging application that they were maintaining.
Couldn't disable the account, cause the messaging is a critical process (inter-bank money transfers). Could change the password, but would have had to tell developers so that they could configure the messaging app with new password (and the app keeps the password clear-text in it's properties)
The security officer threatened them with diciplinary hearing and possible dismissal, but management did nothing more than slap them on the wrists. They were 'valuable employees'
When SQL 2005 SP2 came out, I dumped a login trigger on the prod box that rolls back any connections that cme from the app's login that use a querying tool.
The screams were soooo pleasant to hear.
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