I disagree. It is not their job to troubleshoot a customer's lack of computer literacy. All they can do is give the customer the info requested. If the customer has technical difficulties on their end, that is not their responsibility and is beyond the scope of their duties.
It could be something as simple as needing to clear the browser's cache. But if the customer doesn't know how to do that, the CSR may well not have any knowledge of the various browsers between Windows and Mac PCs and be unable to help nor should they be expected to..
I believe that I have above average computer literacy. Apple Safari is a popular browser, and half the OP web page worked, name and address sections, but Not the Order page. I dare say that is a problem with OP's web page and Not my literacy. I do believe that OP's Customer service should be familiar with problems associated with OP's web page and should be able to advise customer how to work around those problems. My experiences have been that generally there are always more than one way to do something, yet OP's CS refused to offer any way to work around the issues with their web pages. That IMHO is horrible Customer service.