Our landland started having static whenever it rained.
It got worse and worse until we could hardly complete a call.
The phone company sent technicians to our home. there was not a single one who know how to diagnose landlines; so our landline is now down forever.
!WINE
If they're still charging you for that landline service, then they either need to fix the problem or reimburse you for any amount of money they charged you for which you did not receive service. If I were in your shoes, I'd be looking for every way to ruffle their feathers until they made you whole. If they can't fix your landline phone service, then it's their duly obligation to find someone who can fix it or give you all your money back.