I'm not at all sure how you've come to take offence - you've had a very straight answer to your site's problem, namely that the image filesizes are too large and need optimising.
I pointed you at exactly the place to learn about how to do it "by the book" - and offered an alternative solution (i.e. instal ImageHandler) to make your life easier. Your response of "if I make the thumbnails any smaller etc" suggested that YOU were the one managing your images, and if that's the case, then neither your host nor the person who built your site (whoever they are and whether or not they are the same person/company) are responsible.
If, on the other hand, someone else IS completely responsible for building your site, then yes, it is up to them to rectify this issue.
Now - if it's any consolation, I too was utterly confused by Merlinpa's comment :D and I now see who your host is; as it happens, I have recently been engaged to help develop another store hosted by them, and as far as I can recall before I upgraded it to 1.3.6, all the image directories were where they were supposed to be...so you should have images, images/medium and images/large in your site directory.
The fact remains that your site is slow loading because of the images. Somebody needs to fix it or you've wasted your money in setting it up, because customers will not wait for the pages to open. No offence intended!!