Hi - I have a LHR - BKK return and wish to change the return date - fare basis ZNN28V2R.

I go to change the return dates - to new flights with Z class - and the website is coming up with a change fee of £936 per sector on the initial page, and then if I click through and look at flights its coming up with £1262 (on numerous dates, some other dates are higher).

The EF fare rules - and what I remember when I booked - has a £305 change fee.

I'll obviously need to call rather than use the website but will I need to be very persistent or should it be straightforward? Anyone have similar experience with this?