You are outside Argentina yes? Many shops and businesses in Buenos Aires will deliver goods if you ask them to. If you are in Buenos Aires just go in and ask them. Otherwise, one way to locate one of those businesses would be to use Yellow Pages on the internet: http://www.paginasamarillas.com.ar
Under the tab for businesses (Empresas) Search (Buscar) for Vino
Narrow the search down (Acotar tu busqueda) by location (lugar) and select the location nearest to your friends
Many of the businesses you see there will offer a phone number, an e-mail address or a web site but when you contact them don't expect them to read or speak English. Choose the medium with which you are most comfortable. If your Spanish is not up to scratch, ask a friend to help you. If that is not practical then perhaps you might find a business with an easy order form on their web site (Google language tools can help with this) or you could send them an e-mail. If you don't write in Spanish, my advice would be to write the subject in Spanish - something like quiero comprar vino - and write the rest of your message in short, simple, clear English. By all means use an internet translation engine to understand their reply but do not use one to send outgoing messages. Trust me, it will be a mess. Far safer to let them find a translation at their end.
One other thing. Argentina is one of the World's great wine producers so don't expect to find many US, European or Australian wines on offer - any more than you would expect to find foreign wines on sale in France.