Closing a group

Been with Smarty for years and had a group plan. Connection became abysmal, so closed my main phone account. 

I cannot now log in / see dashboard etc because the main account is closed. How can I terminate the sim thats still on the group account? No way of contacting SMARTY directly. All 'help' questions/replies do not cover the messages I receive. 

The usage on the existing SIM is nil, as there is NO reception where I now live.

Thanks for any help.