Most copy shops can do this- I use one on Santa Fe near aguero, but any of the bigger ones will usually be able to do it. Nowadays, they will scan it and digitally fax it from a computer, but the recepient cant tell the difference. There are a bunch of big ones near univesidad palermo, on cordoba and bulnes or so. But there are no doubt places in the areas you mention. Look for a place with big format printers (1 meter wide) and large copy machines. there are also websites online that will take your digital image and fax it for you, for a fee. I have never used one, but there are several of these.