DWP not sending PIP decision letter,unable to lodge reconsideration / appeal

Strange situation.
PIP was stopped following review.
I never received the original decision letter.it was decided and immediately stopped over 1 month ago.

so far I've called them twice,first call was 1 month ago,they told me they will send a new copy,nothing arrived after 2 weeks,I called them again (nearly 2 weeks ago) I was told they will send another copy.and that they will put a note on my file that I haven't received the letter,I was told if will be ok even if 1 month deadline expires,and that there is a "situation" with post and letters can take 1 month! to arrive.

post is working as normal,we receive other mail without delay.including a letter from ESA showing reduced rates (because of failed PIP review) which arrived very quickly.

I don't believe they've sent the letters.there is no way post within UK can take over a month to arrive.
and I can't ask to reconsideration or appeal without their letter.

has this happened to others?
any advice or suggestions what can be done?

I called them again (3rd time) they had the history of previous calls.
they said they will manually print and send it again since sometimes their system just doesn't print and send these letters.

strange how their system works flawlessly and instantly stops people's payments on the same they decision is made yet doesn't even print the decisions letter.

hopefully this time the letter arrives so I can start the reconsideration and appeal process
.it's been nearly 40 days since my PIP telephone re-assessment was decided and refused.