Is that a Sony 'all in one' type system? Please provide more details so we might assist. I didn't see anything online. Understand, the models we see here across the pond may not be the same as the numptys see in Edinburgh
Also, it would be helpful if you uploaded a few photos of your current connections/wiring. I use imgur.com for just this type of thing. Just post the links back here after you have uploaded a few useful photos of the wiring/etc.
I'm complete AV numpty and just got a pioneer vsx-521 receiver with ssh50 speakers and subw. The 5 speakers incl centre are identical the only thing that differentiates is colour codes on the connection terminals on the back - one with green/black, two with red/black and two with grey/black. In connecting I figured green must be centre as there's only one and then assumed red/black ones for the front right and left. This doesn't work and it's driving me mental! Receiver seems to be working fine with display etc.. and the connection between LG 55 tv through a hdmi cable recognises the receiver is there as when the receiver turns on the tv sound cuts out and when I turn receiver off the tv comes back on. Searched for a ssh50 manual, wiring diagram etc online for days and there just isn't anything I can find