Golf Mk.5 RCD300 Aux Input HELP!

[ppksam]

Guys,

I have an 05 Golf Mk.5 with an original RCD300 head unit fitted. I want to be able to play my iPhone through the unit using a 3.5mm jack. I don't need to be able to use the head unit to choose tracks etc. and I don't need the head unit to charge the phone (I have an in car charger using the cigarette lighter). I basically just want to hook it up as an AUX in.

I recently purchased this:

http://www.amazon.co.uk/gp/product/B...?ie=UTF8&psc=1

After attempting to fit it today I couldn't get the iPhone to play through the system at all. Having done some additional research I can't find any article which shows me how to fit a simple AUX in cable.

My question is, does the RCD300 have AUX in compatibility or do I need one of these:

http://www.ebay.co.uk/itm/VW-AUX-inp...p2054897.l4275

I hope you can help and appreciate your time.

Sam.