Unjustified harassment by a corporate

Below is an email that I sent to Trifecta Capital yesterday. The email address that I used is from one of their numerous letters that threatened ne with summons. The email bounced back with reason: This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: *** Mailbox trifeudi is unattended Dear Trifecta Capital May you please refrain from harassing and threatening me regarding this account that I settled with Design School Southern Africa in 2012 already. I have sent you proof of payment and confirmation of settlement of account letter that I received from Design School Southern Africa numerous times, but you are relentless in your harassment and threats. I am unemployed, I don't have an income but owing to your incompetence I end up using money for food for my family to call you explaining the same thing and getting promised resolution to no avail. I last spoke to Roxanne at your call centre on ‎29 April after receiving yet another threatening text message from you, and she promised resolution same as she had done so on the 16th and 19th of October 2015. This is very frustrating to say the list. Please resolve this matter and email me confirmation to that regard. Yours faithfully Veliswa Mambi Sent from my BlackBerry 10 smartphone. ------------------------------------------------------ Hellopeter, please assist me.