ST Mondeo Stereo Aux in and USB

[Marty V8]

Hi,
Apologies if this has been covered before, but the search function isn't working at present.

Ive recently got a 56 plate ST Mondeo fitted with a 6CD sony stereo, which also has the aux socket in the glove box. Anything plugged into this aux socket is not controlled by the stereo which means if I want to look for tracks I have to search using the plugged-in device rather than by using the stereo controls, which is a bit dumb and also makes using this a non-starter when driving.

Is there a way in which I can upgrade the unit to take a USB or MP3 player (or are there any inputs in the rear of the unit suitable - Ive not had it out of the dash yet), whilst still retaining the existing voice control and steering column mounted remote control? I dont really want to swap head units unless its for another fully compatible Ford unit, and I also dont want something that looks like an epilepsy-inducing mobile disco either.

Advice gratefully received. Thanks.

Regards

Marty