Harrasment

I took out a personal loan with African Bank which I have been paying consistently every month. Now my problem is there is a man with no t-shirt or job card to confirm that he works for African Bank.

He came to my home and showed me papers with my information on it saying African Bank sent him to update my information. The man showed up again( second visit, and he comes on a Sunday) requesting that I should send my proof of payment to a certain number also the legal department....

Now my question for African Bank is why would you send a stranger to my house on a Sunday.? I am paying what is due every month, what is the purpose of this man coming to my home?? I need an answer on this because I'm starting to feel harrased!