Mike,
I'm sure I'm a very valued customer, but I'm also sure they waived nothing for me!
However, I did think after posting that I might have been unclear, or even unsure myself.
I think the point must be that I'm not making a Chaps transfer at all, but a BACS one (which takes 3 working days and is free). I know that IB say it must be a Chaps transfer, but I just setup an online mandate (which I'm pretty sure can only be BACS) and it worked fine (twice). I think I did talk on the phone with ANL, before sending it, just to make sure that the info they had recorded matched what IB asked for. You have to wait a couple of days after setting up the mandate (the first time only), then 3-4 days for the funds to appear in the account, so it isn't quick, but it is free!
Have you tried ringing IB customer service to clarify this? I'd be interested to hear what they say. However, I can see no reason why they can't accept BACS, it's just a bit slower. It think the point they are trying to make is that they don't accept cheques or cash.