THE
They legally don't really have a choice.
Under EU regulations they have to provide you with reasonable alternative routing that suits you.
Also I think if you really push it they must actually find you an alternative routing for your day of travel with an alternative carrier that they have to rebook for you.
That could be an interesting fight I think!!!!!!
Again this is covered under the same section of the EU regulations.
Most airlines adopt a bit of a bully boy approach and don't tell you all that you are actually entitled to.
As i said yesterday they have offered Thursday as an alternative as it suits them.