Posting on behalf of my husband who can’t use his account

what on earth is going on.  Husband wanted a new phone number as his old one was getting rediculous amounts of spam so phone calls.  Anyways as he was with smarty as I am, he asked for a new number and to cancel the old one.  Discovers 2 months later that he’s still being charged the plan for the old number. Now he’s spoken to someone on chat who said don’t worry they’ll sort it. Well they haven’t.  He’s just spoken to someone again in chat who clearly couldn’t understand what my husband was saying due to the language barrier. To make matters worse Smarty closed his account with the new number and he is using his new number and is being charged for the plan. For Lordy sake how can we get this mess sorted out?