Not receiving correspondence back from HMRC

Dear Sir or Madam, Each year I send documents to claim a refund of withholding taxes to HMRC by post. I include a cover letter asking them to kindly sign the document for me- this is a standard form issued by the French tax office that must be known to HMRC and they have stamped and signed it for me in 2019. I have sent the same form for years 2020, 2021 and now 2022 but never heard back from them. Is there any way to chase this up please other than post? I never receive an acknowledgment or a reply. Many thanks for your help.

Hi,

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Thank you.