As has been covered many times before and for the benefit of anyone else wishing to switch membership types, no, the invoices cannot be changed, they can only be paid, cancelled or deleted.
In your case @Bananaman your current membership package with posted printed magazines expires on 22 March. Once it expires, log in and go to the Store tab at the top, then choose WSCC Membership, then the electronic magazines package at £35
Why wait until it expires? Because they are two different membership packages and they do not interact with each other so if you bought it now, they would overlap each other and the electronic one would expire in February 2026, shortchanging you on your existing membership by one month.
Of course, if you wish to give the club extra money to get less, I’m sure they would not object, but I doubt that’s the case!