Zeon: You are going to basically get the same performance no matter if your "business" or "residential" if you are going mainstream ADSL. All the ISPs including Telecom retail can only provide what Telecom Wholesale has available so best to try to talk directly to Telecom wholesale maybe.
Your other option is to get a true business connection like SHDSL which Telecom wholesale call HSNS (most ISPs offer this) or a wireless service.
actually there is a significant difference in the quality of the internet between providers supplying ADSL connections, especially in the international internet connectivity - which the OP stated was an issue. AFAIK, ISP's source their own international connectivity, telecom wholesale is only selling the adsl port and the backhaul from the exchange/cabinet back to the ISP.
HSNS/SHDSL, wireless and other options certainly make sense from a upload/download speed ratio and for extra cost you''re also (hopefully) getting less contention on the international links which should make it faster..