Found it, thanks. I've been through a similar process to you - took my SS at 62, started my UK state pension when I turned 66 last Sept. By that time, I think when I turned 65, I'd already had SSA-308 forms to complete - in which I stated that I'd be getting my UK state pension at 66, value at the time unknown, and other pensions I didn't intend taking yet. They seemed happy with that and it didn't affect my SS.
When I received my award letter from DWP, I duly filled in a SSA-308 and sent it to the FBU (I'd learnt by this time that you can send stuff to them). This was early August 2023. I have only in the last couple of days (almost a year to the day) received the correction letter - basically they've been overpaying me and now want repayment. The mechanics of repaying them seem impossible, so I'm minded to take the default option and not repay - in which case they'll start withholding 10% per month until they've recouped the overpayment. I've covered all this in the thread entitled "Delays at the SSA" on this forum.
I will have to go through this all again if/when I start taking my UK workplace pension(s). I've deliberately delayed taken those even later - I didn't fancy my chances sending more pension updates before they'd even dealt with the first one.
Suffice to say, I feel your pain. Nothing seems easy dealing with the SSA/FBU. The absolute best thing is getting monthly deposits directly into my UK bank. The absolute worst thing is the thought of having to repay them some money - international bank transfer, no, USD money order from the UK, impossible, USD cheque from a US bank, if you're lucky.
Glad you found it. I did come across your other thread yesterday but was on my phone which, as you may gather, I struggle to negotiate. Now at the PC and will take a look at it later.
I'm now 16 months post-WEP date (i.e., past commencing my UK state pension) and currently guesstimate that they have probably overpaid me by something like £4,000-£5,000 so far. If I end up in the same situation and they ask me to repay it, I'm hoping they will just deduct it from future payments (or even stop paying until it's reimbursed).
Regarding the COLA adjustment in your following posts, I recall reading that the amount of WEP is fixed at the amount determined at the assessment date (which in turn is the amount DWP have said is your starting pension) - but it seems plausible they would make a COLA adjustment to that each year, concomitant with the COLA uprate in SS pension. I don't know for sure, though.
Other than possibly trying to call FBU again on days I have the impulse to do so, I've given up on it and am just waiting for them to catch up with things as they did in your case. I have kept a rough record of what WEP is likely to be and consequently how much I have been overpaid so that when "D-Day" arrives the amounts involved won't be a surprise.
My situation is somewhat complicated by the fact they needed to get information from DWP on non work-related NI contributions dating as far back as 1973 (secondary school NI credits) - they have confirmed that they now (as of about 6 months ago) have this information so maybe if the wind blows in the right direction I'll hear from them some time in 2024. I won't lose any more sleep over it, though.