Hi beverley, they HAVE to record every call, along with the date & time (to the second) so if they tell you any different, they are lying. (The recording is done automatically, but the recordings can be deleted, accidentally!?!)
Unfortunately, the Tax Credit call centres (along with all HMRC call centres) are staffed by people who have had 2 weeks training at the very most - they are given scripts to read out, with no understanding of what they are saying, and no background, so they do not understand how TC work.
This is a reflection of this Government (and the previous one)'s attitude to so-called 'customer service' - i.e if you claim any sort of benefit, you are not worth bothering about.
Sorry but you were lucky to even get through to the TC helpline! I have tried to call them (am, pm, evenings & weekends) but either got the busy tone or was put through to a recorded message thanking me for my call, asking me to try again later and hanging up!