Maya Shop category picture problem

Hi,

I was wondering if anyone can help please. I have just updated Maya shop theme and everything looks okay apart from the pictures in my categories (not listings) have gone oversized?

They were 200×200 but now they seemed to have stretched and I can’t in the life of me find out how to get them all back to their original size without having to change each one, 2000 will take me forever.

My website is http://www.conquestcarbon.co.uk

I would be very very grateful if someone could help me.

Thank you