Confirmation of Payment Request

I have been, for the past 18 days, requesting confirmation of payment (on a letterhead) of an amount I have settled from this company without success at all!

I have been in touch, numerous times, via email and by phone with an Althea du Plessis who completely ignores my emails and provides useless excuses when I call her, instead of providing me with a solution she effectively tells me it’s not her fault, it’s another department that should send me the letter. I have asked her numerous times to follow up and get back to me. She has not! Surely it does not take more than 18 days to do this? I am at my wits’s end, what on earth do I need to do to get this simple piece of document?!

This is the worst service in the world!