faulty product

Good day all<br> <br> I bought a bran new hilinK e3531 MODEM FROM COMPUTER MANIA that is beyond faulty. it is supose to be able to connect using any network but rejects cell c and keep on reconnecting mtn even if i'm within 3 km from the tower.<br> <br> i took it back and they told me that they cant exchange it because there is an scratch on it but only they can see it because i cant.they sent it away to their techs and they sent it back telling me there is nothing wrong because it functions within specs. i disagreed because in their shop the modem keeps on connecting to 3g but not hspa as the box suggests. now i can barely post this complaint due to connection problems.