@splashingpixels.com - thanks for clarifying things, although, I came here to seek help, not spread alarm. I'm not sure how using uppercase words at me, as you did earlier, helps. But ok. I accept what you're saying, and I'm not here to cause problems, just to get help.
Please here is a quote from the developers themselves (Woo):
For the most part, WooCommerce templates will integrate nicely with most WordPress themes. Where you may run into problems is when the default WooCommerce content wrappers do not match your chosen themes. This will manifest itself by breaking your layout on WooCommerce pages and shifting your sidebars into incorrect positions.
This problem can potentially affect the shop page, the single product page and the taxonomy pages (categories and tags) because WooCommerce uses templates of its own to display these pages (and its impossible for WooCommerce to know exactly what markup your theme uses)
I got that quote from this url:
This URL describes the problem, as well as offers their recommendations. So you see, I wasn't just making things up to "scare people", as you say.
@Novellis - If you have purchased a premium theme, you would be better off contacting Woo support before making any changes. If you are working with a free theme, please consider the link I presented above, in addition to the other advise you have received from everyone here.
In case you don't have a developer to help, take a look the Woo recommendations at the bottom of the page I have linked to:
If all else fails…
If you cannot work out the above methods, and don’t have access to a developer, we strongly recommend looking at our WooCommerce Themes which work out of the box as a hassle free solution.
This is their own words, not mine. What I consider strange is that my client was using a WooCommerce Theme. I'm not sure what that says about the developers and their products. I'm all for quick fixes and so on, but for busy business people who are not developers (e.g. creative fashion designers), it can be a real problem when things don't work as they should after you've paid for them.
Having said all that, I don't think Woo-Themes are supported by wordpress.org forum, anyway, so there.
Thanks to everyone for their support and help.