My Krungsri account was about 10 months when it was deactivated, any transaction in that time just paying in a couple of hundred baht would have kept it live and saved an awful lot of faffing about at a branch 22 copies of everything and payment to get a new card and activate the account.
Lesson learned, today just transferred token amount from my main account to keep it active, could you do similar online transfer from the Uk or have a friend in Thailand who can pay any amount in to the account which will keep it active.