Complaint to ATOS/IAS

Hi.I have submitted a complaint to ATOS/IAS following my home f2f as part of my PIP review.
I'd been informed of the date and time that a HP would attend and the day before was phoned and given the name of the HP.
On the actual day there were 2 people not one and the named person didn't do the assessment. Even though, due to my mental health issues, I said how stressed and intimidating I found it when changes were made, I got no explanation and my comments weren't mentioned in the report.
The 'assessment' and report tell basically the same story as many people have experienced, in particular:
Not considering all the evidence supplied.
Making unsupported, subjective, often inaccurate, statements and then using them to dismiss professional & carers evidence to the contrary. This included dismissing a test result from my DLA-PIP assessment in 2017, even though the 'Health Professional' this time didn't do the test!
I haven't (as yet) received the DWP decision letter.
I was wondering if anybody knows how long it may be to get a response to my complaint to ATOS/IAS?

Also, I was looking to email my complaint to ATOS/IAS and couldn't find an email address in their leaflet on complaining. My wife phoned the number given in the leaflet and was told there was no email address that I could use to send them my complaint!
Yes, in 2020 an organisation which is employed by the Government to deal with disabled people won't accept an emailed complaint. Instead the complaint had to be printed and my wife did a 24 mile round trip and pay postage for a tracked delivery option!
The final irony, of course, is that in getting my complaint accepted, my wife had to use the Motability vehicle that the report would mean I'd have to return!

I made a complaint. They had 20 working days to respond. The response was very thorough and a second home based face to face was organised.

Thanks for that.

I have sent my MP the details of what happened. I hadn't thought of complaining to the DWP but will certainly consider it now. I was concerned that it could get 'confusing' if I have to complain when I'm informed of the decision.
I actually felt from the start of the f2f that it was going to be a 'hatchet job'. The HP who did my first assessment was the one due to do this review one and was the accompanying person. I felt that she was being 'shown' how to minimise any points. I put it down to it my anxiety but when I read the report at least I was able to say it wasn't just me being paranoid!
I think I was surprised at how planned it seemed. So, rather than 'the claimant was in his nightwear' he was 'casually dressed' and to not record things that supported the awarding of points.