TS_500

I am a British citizen tax resident in Italy. I received a lump sum from my UK pension provider in December 2022 which I was informed had been taxed at source in the UK. Following advice from this forum, I submitted DT-Individual to HMRC, with a Certificate of Tax Residency from the Italian Authorities, requesting a refund of the tax so that I could submit the full amount for local taxation in Italy. My provider was, for some reason, reluctant to inform me of the tax paid, but I assumed that HMRC would have the details. HMRC recently replied with a refund of tax that had been paid on my monthly pension, but saying that: 'We don't hold details of your lump sum payment so are unable to exempt this source of income or review for any potential repayment. Please provide a P60 or document confirming pay & tax' I already had a P60 from my pension provider on which there was no mention of my lump sum or any tax paid on it, so I contacted them requesting further information. I have to-date - after over a month - not received any response from them and so have solicited them again about it, hoping for a reply. I was very surprised by HMRC's reply that they don't hold details of lump some payments - and tax that they have collected from them. Is there any way that this information can be found or derived...? I need the to know the full amount (Lump Sum + Tax deducted) to submit to the local Italian Tax Authorities. Any assistance or advice would be greatly appreciated.