Statement of tax liability - The Netherlands requested 7 months ago

Hi - I have been waiting now 7 months for a Statement of Tax liability to be signed. HMRC have received it back in May. Its a single piece of paper that once signed allows the UK to claim tax on a foreign pension. So it's in the UK's interest to sign it. I was promised it in June, then October and now, today, in December. Is there any way possible to get this done any sooner?

Hi ICB,
I am sorry if you have not yet received your requested statement of liability.
To check on the progress we would need to access your record.
To do this you will need to contact HMRC:
Contact HMRC
Thank