Thank you for your help on this Craig but still pulling my hair out!!
It seems that whenever I use a session variable within the shipping of the eCart the shipping option is no longer recognised and is ignored.
If I set the shipping to items in basket greater than 0 and set a flat rate of £8.00 this shows up on the confirm page but as soon as I change it to session variable nothing shows and the total does not include the shipping.
I know the session variable is being set as I have added a php echo at the bottom of the shipping address section which then shows the value of the session variable so looks like that works but eCart is just ignoring it. Unless of course I am missing something really stupid here. You mentioned above to set the value of the session variable to the value of the list option. can you confirm how I do this in case as I said I am doing something really silly.
Also you mentioned testing the session variable in the shipping section of the eCart. Is there a way of doing this other than what I have already done?
Any ideas where I could go from here?
Thanks again for your help.