Run the numbers.
Imagine this client generates €3,000 per month.
But your team spends an unpaid day every week servicing them.
Then add every moment you have to step in yourself.
Now include all the frustration that can't be measured in hours.
How much of that €3,000 is actually left?
And what could your team accomplish if they had that day back?
If you decide to end the relationship, do it professionally.
Give reasonable notice.
Provide a clean handover.
Don't burn bridges.
You don't need an argument.
You don't need to defend yourself.
You're simply restoring your standards to where they belong.
One important distinction.
This is about a client you're already working with.
If a new prospect doesn't have the right budget before they become a client, that's a different conversation.
In that case, you simply decline the proposal.