Large testimonial slider to far right on mobile

Hi,
I have a testimonial slider on this page: http://www.caseyandassociates.co.uk (scroll down to it).

It is fine on Desktop but on mobile it appears to the right and off the screen!

I’ve tried adding this CSS:
@media only screen and (max-width: 479px) {
#top .av-large-testimonial-slider.avia-testimonial-wrapper .avia-testimonial { padding: 0px 20px 0px 0px !important; }
}
This helped a little bit but increasing the padding from 20px doesn’t make any difference.

On a side note, I have also this to hide the arrows on mobiles:
@media only screen and (max-width: 768px) {
#top .av-large-testimonial-slider .avia-slideshow-arrows a {
display: none !important; }}

Is there anything else I can try so that it is centred rather than too far right? It is ok when I resize my browser so t’s narrow but not ok on say an iPhone 5.