Yes.
The best is going to any:
Carrefour (also mini or express) or farmacity or any branded shop. They don't charge anything else but the amount you want.
Also considering:
* buying pre-paid packs with your credit: It more cheaper (or less expensive)
that pay along you use.
website.
http://www.personal.com.ar/packs/home/index.html
examples:
AR$15 pack SMS+Voice: 100sms+100minutes: Expires 7 days after activation.
so: you finish paying 60 monthly for 400sms and 400 minutes!
(standard prepaid minute is $2!!)
How to activate this pack?
Send a text message to 152 with "ACT PPTI15" (without quotes)
Voice packs:
Night: 200minutes, from 21 to 9am, 5 days, AR$9
friend: 720minutes, just 1 personal number, choosen,
call to 'personal': with this pack you just pay the first minute of every call. AR$9 , last 7 days