Activation Fee ?

Hi, can I get some help here too? 

Recently just upgraded to the 1GB after being a week away from my 30 day leaving period end date i have had a lot of stress and difficulties trying to get a semi acceptable upgrade deal. Finally i get an ok deal and I've been stung with £40 "installation/activation" fee. None of this was explained during the upgrade process. I find out through an email. Had it been explained, I would have said no as I'm not prepared to pay an activation fee for a line that I already have been using for years now. 

The service is really terrible here and I'm hoping someone here can begin to change my perception.