IDA Law useless bunch of blood sucking ambulance chasers

what a useless company they send demanding and threatening sms and phone call even after you have settled your account and sent them proof of it no one will ever get back to you and send you proof of this it must clearly be a bottom of the barrel law firm that can only hire dimwitts who cant do there job i would like to know if there is a law against this type of harrasment and how i can institute a charge against them as im fed up now and i believe they need a taste of their own medicine