Product list not lining up in categories

Hi, thank you for your help.

Could you please take a look at my site as I can’t work out how to make certain products lists line up. They become staggered when a certain product listing is longer than the others in a row. Here is a good example: http://www.booktravelandtours.com/travel-quote/.

Also, I have created 4 voucher products and would like them all on the same row, however, despite changing the settings in ‘customize’, the row remains at 3. You can see on this page: http://www.booktravelandtours.com/destinations/australia/

I will be in touch with details. Many thanks