Long Term IB - When can they ask for medical cert?

Reminder of situation. Was on long term IB end of last year. Then started reassesment process to ESA, a medical assessment was missed due to me not receieving letter of appointment, they terminated my benefit, I appealed, they reconsidered the decision and I was reinstated but put in clerically offline status. Initially no mention of needing sick notes been needed just told I was back to where I was in the reassessment stage and I should expect a new appointment for a WCA.

This is where things started going weird.

I then found out I could have my WCA recorded so I requested it, this led to my existing appointment been cancelled as one was already booked. After it was becoming clear there was going to be a noticeble delay lasting for months I was told over the phone I needed to send in sicknotes, not on assessment rate ESA, I am on long term IB. I sent in the sicknotes for about 2-3 months. Then when a WCA was booked (non recorded) they told me over the phone again "not to bother" sending more in, they realised wasnt needed. Meanwhile I was in fight with ATOS/DWP over the recorded status of the WCA and eventually ATOS backed down, the WCA was cancelled again but only by a few days and I had a recorded WCA 3 days after the other appointment. So now I have had the WCA.

Almost 6 weeks have passed since the WCA, today I got a letter saying my medical cert ran out on the 26 june, thi sis the first written correspendence I have had at all about this, every other contact has been on the phone regarding the certs. When I spoke to them it seems they think its perfectly reasonable to expect me to ask my GP for a 2 month backdated sicknote and especially when they told me there was no need to send them in, a friend has advised me to write a letter of complaint asking where in the regulation it states long term IB claimants awaiting a WCA result need to send in medical certificates. I have the exact name of the staff member who said I no longer need to send them in and even have the direct number to her office, today she refused to come to the phone to speak to me, my request to her was to confirm to the DWP department to verify she had told me I no longer needed to send them in.

My question is mainly down to is it regulated for this situation to require medical certificates. I am not in appeal status, and I am not in assessment phase.

I am on long term IB and thats whats going in my bank, last payment 3 days ago, basically the payments havent stopped. They were only stopped when I had the non attendance issue earlier in the year.

So it sounds odd to you as well then?

Do you have advice on how I could challenge this?

On my bank statement it says my insurance number and DWP LIB. The amount is clearly not ESA.

The letter asking for the med cert is headed incapacity benefit, and the box ticked as reason is "pay you incapacity benefit".

So to confirm yes I am not on assessment rate. I am on full long term IB rate with age addition.

Thank you.

Yes I did wonder if a WCA decision came soon would that resolve the situation, although I also worry they could still suspend future ESA payments based on the gap of medical certificates. My plan is to ask my GP for the certificate (regardless if I complain or not) taking the letter with me to explain why for such a long backdate, but I suspect there is a big chance he will refuse to backdate so far.

I got it fixed, the lady got back to me and said they sent it in error. Thats all the info I got on it.