so I'd agree with what @lucaskauffman and @terrychia have said so far but here are some more tips that might be useful to you in improving the control over your dev environment. Ultimately you should try and get to the kind of control level that lucas mentions but it might be a hard sell to jump straight to that so there's some intermediate steps you could take.

• Start by moving devs from read-write access to production to read-only. Introduce a change control process so that changes to production data are staged and applied in a controlled way, not by individual developers. If developers need to try things out then introduce a pre-prod environment and try things out there.
• Remove developer access to the server. Change management for all code changes, developers shouldn't have direct write access to the production server, one of the nice things about git is that it's easy to have a copy of the code so hopefully there shouldn't be any circumstances where direct code changes would be made to prod.
• Once you've got people working that way, ideally you wouldn't have people working on live data at all, they should work on anonymised sample data which reduces your risks of losing customer information. There are tools to anonymise data but even something as simple as a script which replaces names with Mr M Mouse and the like could help reduce the impact of someone taking a copy of the database away with them.
• if you can get as far as this point, then look at taking things further (e.g. COBIT/ITIL style models)

The huge point about all this is it will require good levels of buy-in from your management. all these steps cost money and will slow down the development/test process in the short term (in the long term they'll likely save the whole company though).

Getting that buy-in may be tricky if management don't see the problem. I'd suggest searching for horror stories of uncontrolled dev. environments, of even better if there have been problems in the one you're working in, use these as examples of things that could be avoided by adding a bit more process to things.