I just had cause to ring Easyjet for two questions.
Rang 0843 1045000 and option 3.
Call answered within seconds.
Question 1. Can I cancel a booking and get my taxes back.
Answer. Yes of course, what's the reference? Confirm last four digits of card. Money refunded
Question 2. I have entered Advanced passenger info but will be getting new passport, is it okay to change details.
Answer. Yes of course you can.
Total call less than four minutes.
I don't understand all these other problems people report about this service. It is excellent.