Harassing me although my bill was never in arrears

I had a phone call from Jade saying my Altech bill was in arrears on 14 January 2016 at 15.00. I emailed her on the same date at 16.12 proof of my January bill and payment. I received no email from her to say that she has received my email and that the problem was sorted or apologise for the wrong info or nothing. I have also said to her on the phone, that if she did not receive an email from me the next day, then she was to phone me because it then meant that the email address she gave me was wrong. I emailed her again on the 15th to find out if she has received my email but till now I have not received any correspondence from her. The respective emails also never came back saying it was a wrong address. On the 10th of February I received a sms saying that my bill is 120 days in arrears. I ignore the sms, but was again harassed today the 15th of February with another sms threatening legal actions. I have now again send an email with my February bill and proof of payment. I am sick and tired of their incompetency and harassment, and maybe hellopeter will get a response from them because I don't.