Ridiculous outsources

My account was handed over to Easton Berry Collections as I was under debt review and I cancelled it. I have been paying my account every month, now I settled my account with Easton-berry Collections on the 9th February 2018 and since then, the service that I have received from them is just out of despicable. All I requested was a paid up letter to be emailed to me, I even escalated the queries to the supervisors with no success just for a paid up letter. I phoned them this morning again and the call centre agent dropped the call on me. Since I am with Easton-Berry Collections because of Capfin and am a client of Capfin, please intervene as this is really unacceptable behaviour just to get my paid up letter