old website caught in cache?

I took a look around but really don't know how to addess this problem, so if there is a topic please point me in the right direction.

Here is the issue. I have a client website, (I may link to it if I can get some mod authorization, pending that the it's actually needed)
The client is not so happy with me because they have been to two major bank locations already looking talk about their business. When they go to the website their very old site is what's pulled up. I'm talking about 3 months ago here. There is not a thing that has remained the same. Of course this does not look good for them.

Now I have not been with them during either of these outing, nor will I be in the future, so I'm not exactly sure what the problem is here. I can imagine that a large banking institution will cache pages for whatever reason, but 3 months is a great amount of time to let all that go and at least pick up the second iteration of this site (now on the 3rd). What am I missing?

I am running a PHP site on a Redhat server. Let me know what other information I can provide.
thanks

There are a few things you can that may help.

I am against the use of no-cache headers form PHP or meta tags on the document but you can use them.

They would instruct the caching server to renew that cache NEXT time the server visits but it all depend on the caching server.

It is really the problem with the caching server and not the user or the site.

The best practice is to contact the caching server and ask them not to cache that site any more.

Good luck

maybe the URL is pointing to a different location to the new website?

This is going to sound a bit inane, but did you instruct them to see if F5 'Refresh' would reload the site?

I assume you've tried viewing the site from other machines outside your & their networks and see the current site design. Has the site moved ip/domain addresses? If so you might want to check nameservers.

Thanks guys for your help and suggestion.
I'm fairly sure that they didn't try F5 or a refresh of any kind, could be wrong, but I would not expect it of them either. Maybe this is just stereoype, but we're selling a fishing lure. I don't suspect there is going to be a whole lot of computer savvy floating around here.
As for the name server, we actually host the name server and so it has moved. Given the amount of time though I would have figured that this penatrated down. 1 month was reasonable, but 3 just does not seem right.
I have taken a look into the suggestion of no cache PHP headers. This does seem the course to take, though I'm not a fan either. I will be using it on the index page only and hope that it works.
thanks again for all your help guys!