Seller has added on postal insurance without asking if I want it.

[chipmonkey]

The listing didn't mention that this would be done. Am a bit peeved as the postage is already a bit high for the item but at least I knew that before bidding. Can I ask them not to charge for postal insurance ( and not to insure the item, obviously)

If it wasn't included in the original p&p ie it's an extra, then no, they can't charge any extra.
Insurance is for the sellers benefit and so sellers should simply include it in the p&p - this seller hasn't it seems, instead they have used the option box for insurance (am i right?) which means that you the buyer can opt in or out.
I'd message them and say you don't wish to pay the extra for insurance and would they be good enough to send you a new inviouce.

SLM, thank you so much, she has now sent me another invoice without the insurance.