Facebook Block not responsive

Hi there,

We've noticed today that while the Twitter and Youtube blocks scale down well on mobile devices, the Facebook block starts going beyond the available width at about iPhone 6 in portrait view (screenshot attached), with a reasonable amount of left and right padding in our template.

Any lower, such as a Samsung S5 or iPhone 5 and it goes well beyond width, looking quite ugly and creating a horizontal scroll when is less than desirable.

Obviously I've had a look at the CSS and can't seem to override it - any suggestions as to how I might fix this problem?

Thanks