Originally Posted by
abligh
Difference in price between A->C->A and A->B->C->A (which is practically nothing in this instance)?
if your night stop is under 24 hours (ie a connection), your ticket was really A-C-A so you are due nothing.
If your stop was over 24 hours (ie a stopover), difference would be calculated as above and likely give you very little.
Bear in mind that whilst being rebooked "at the first opportunity" is an option, EC261 also gives you a right to ask to be rebooked at different dates of your choice, and in your case, this might be a better fit to your needs.