Cash crusaders suck

I bought a car sound from the Vaal mall branch but the terms of warranty say that the sound needs to be installed by a professional. I did not use a professional but asked someone who is very good with sound installation. The sound is not working . We used the same wiring on an old sound and it works perfect. There is no sign of electrical fault. Does this mean my money went down the drain . A whole R480. I feel they're terms are ridiculous bearing in mind that they don't even test their products before we pay for them. I work in retail and work with electrical appliances hence I know that some are faulty. You guys suck