Agents dropping calls

I called the collection department ***, earlier on today requesting the account paid up letter for the the account I settled last year Nov, the person said he will the person/Basetsana who was assisting me to call me back I haven't been called back. Now I called them again 3 time they answer the call and say nothing and drop it. What the hell is this? People must stop working if they really don't want to work. I have reason why I am requesting this and I was supposed to be provided with this letter last year Nov. This is so wrong.