If it only was the customer support that had no clue...
Obviously, the sad thing is, that the developers also don't see through.
Why would they roll out an update that introduces tons of bugs into features that they think they didn't touch?
1. They don't understand the code and therefore the full implications if changing something.
2. They don't have regression tests.
3. Probably they don't have tests at all or at least a very low test coverage. It cannot be explained, that updates contain that many undetected bugs if there was a rational test coverage.
It’s that easy:
If you have a bug, write a test that fails.
Correct the code and check if the test switches to green.
Add the test to the automated test suite and you will never ever have a regression for that bug again.
Just deploy only if all lights are green.
If you have no rational coverage, Start by writing tests for critical code. Add more tests to achieve near 100% coverage.
Don't write any new code without test coverage.
If you don't understand the code that need to be changed, do code reviews with multiple developers and QM.
Don't touch code that you do not understand. First of all, write tests to make sure that after refactoring or changes the code behaves like it did before.
It’s all that basic professional stuff software engineers do for reasons.
In most cases the developers are not even the ones lacking that knowledge but they are told to implement new features with fast return on investment.
What those decision makers don’t get, is the loss of non-investment in quality and security, e.g. by loosing frustrated customers.