debt collecting company ignoring my request for my paid up letters

I arranged with Easton Berry to debit my bank account on 20 February 2018 for the full outstanding amounts owed on 2 accounts. As per our agreement the accounts was settled on the said day. Since then I have made numerous calls made to them requesting my paid up letters and to date have not received them yet. I made one last attempt yesterday to call Easton Berry to send me my paid up letters and was once again promised that it will be send. Here we are 24hrs later and no paid up letters. I find it disgusting that when you owe the money these debt collecting companies call you non stop. However, when the accounts are settled they are unable to deliver the paid up letter.