Method error 500 on website drop down list

[kennysarmy]

We have signed up for some archive material from the "Philip Allan Magazines Archive"

 

Our students log in are presented with a page of Reviews from which the choose the Volume they want from drop down lists.

 

90% of the time it works OK - but annoyingly from within school using IE11 they get the following error:

 

 

when you refresh the page (F5) it then shows correctly:

 

 

I suspect an issue at their end with their coding but under Google Chrome it works fine....100% of the time.

 

Anyone had similar or got any way for me to prove the issue is with them and not us?