i settled the account why are you garnishing me

I had an cell phone contract with autopage years ago . My phone got ****** and when i went to autopage to claim .they told me that i dont have a contract with them and i cannot get new cell phone . However thet handed over my account to Gerhard van der merwe attorneys . I settled the account on 13 September 2013. I have recently been garnished by this law firm . I think this is unfair cause i paid in full and even sent them proof of payment . Nobody ever bothered to respond to my emals . I have proof and willing to supply it again . <br> why are you garnishing me in 2015 if account was settled in 2013. I want it to be removed immediately .