How can we get HMRC to correct their tax rate?

As part of a training exercise I had the interesting experience of using the HMRC on-line corporation tax service yesterday, and guess what? They haven't updated the small companies rate on their pdf document from 21% to 20% for the 2011 Financial Year yet. I thought it must have been an error by me at first, but this is generated by their own systems after the computations and CT600 entries have been inputted. I searched to see if anyone else had spotted this error already and found the following query on a DIY accounting forum:

http://forums.teneric.co.uk/diy-accounting/hmrc-ct600-incorrect-ct-rates-21145.html

Apparently they want everyone to wait until October before using their system for 2011 year ends.

But what about the tax returns already filed using the HMRC system? Presumably they are sending out tax bills with the wrong amount. Presumably we have to write and tell them. Will they be giving refunds to those who don't spot this error, I wonder?

Isn't it wonderful that they force every tiny company in the company to file their tax returns electronically and then can't even be bothered to get the tax rates right on their own systems. I know the reduction to 20% was not known before the Budget but it's been 4 months since then - you'd think they'd have changed it by now. Maybe they are waiting for the Finance Act to receive Royal Assent.

Has anyone else experienced this problem yet? Obviously it's not an issue if you use your own software but there must be thousands of small companies using the HMRC system. What are they meant to do about this?

Chris