Granny

Hi, I receive a pension from Norway for which I have been paying tax in that country, and receiving Foreign tax credit relief from HMRC for several years. On my latest tax calculation I have received a tax demand for this tax year and in addition I have been required to pay tax on previous years back dated to 2022. I moved back to the UK from Norway in 2018. My current tax calculation does not include Foreign tax relief credit. I cannot understand this at all. I have been trying to speak with a technician for several weeks, but they have not called me when arranged, and they have not been available when I called. Has the article 17 of the UK/Norway tax treaty been altered by Brexit ? Please help to clarify this situation, Thanks,