Continuous harassment from NBA

Nashua mobile invoiced me for a cell phone number expenses for the past 7 years. A cell no that does not belong to me. I had an excellent credit history with Nashua but refuse to pay for someone else's cell expenses. When Nashua closed down they handed me over to NBA. I have sent the proof to NBA that I do not owe Nashua any money. But NBA continue to harass me for payment. Their staff phones me over and over again, sends me sms's all the time and sends me e-mails all the time. I have told them to look at my documents that is proof (anybody will be able to see Nashua's mistake) or to take me to court, because I have all the proof that I do not owe Nashua any money. NBA obversely have unqualified staff otherwise they would have noticed Nashua's mistake and addressed the issue with Nashua. Instead of taking me to court and wasting their money on court cases, they choose to harass me endlessly. I am about to take this matter to Carte Blanche and the newspapers, because I am sure I am not the only one subjected to this unprofessional and unacceptable behaviour.