Something does not sound right here.
Yes, and what is wrong here is Rigol.
I have contacted Rigol NA in Ohio 3 times about firmware issues and parts and have received responses very quickly.
I don't know what you did to get a response. I am not in the US, and I can tell you that Rigol in China and Rigol in the US give a fucking fart about requests, even when you are about to buy some of their gear and just need some confirmation about a detail.
I even subscribed as one of their "Advanced members" on rigol.com in the hope to get help and information. That subscription brought me some Rigol newsletter spam, and that's it.
I even had a short phone conversation with a support engineer and was very happy.
See, I seriously doubt there is such a thing as a "Rigol support engineer". It is like Bigfoot. Some people have seen one. Some people even have photographs. Some people believe Bigfoot exists. I don't, because I couldn't get hold of one.
Contact parts and see what happens.
What is this ominous "parts"? Do you have more inside information about Rigol, and some secret contacts to get parts?
Remember you will get more with a dash of honey than a cup of vinegar.
I for myself can say that I can hardly make it any sweeter than expressing a wish to buy some of their gear - but that didn't get me any answers. It is like being in a shop, showing the salesman a bundle of money, pointing to some wares, and telling the salesman "I am interested in this, please.". And then watching the salesman just completely ignoring you.
Let me finish by quoting one of Rigols company guidelines
We respond to our customers’ needs with speed and agility; we demonstrate dedication to our customers’ success by being flexible and accountable; we strive to build and sustain the highest degree of customer satisifaction.
What a steaming pile of lies.