How about; "It appears our services are blocked by some sort of company firewall or security policy on your end. This is an issue that you should bring up with your IT department. If you can advocate to get them to lift the block against our platform we can offer you XXX"
Guess you haven't worked with any large companies... They're always the ones that cause these kinds of problems, not the small flexible ones. Those large companies are also the ones that will pay the most to solve their problems via external services (both due to number of users and how slow it would be to deal with internally).
"That is managed by X department, we can put in a change request and we'll probably get a timeline for the fix at the beginning of next quarter. We'll re-evaluate if you can help with our issue once they get back to us."
You have to balance it against expecting to receive: "That's funny, because we tried a similar product from Slightly Unjust Moral Compasses, LLC and it worked fine. We'll just switch to them. Goodbye."
