Submit an interference report
Advice on how to report Harmful Interference to the regulator Ofcom can be found at https://www.ofcom.org.uk/spectrum/interference-enforcement/interference-to-amateur-radio
One common source of interference is VDSL broadband you can find advice on how to identify and report this to Ofcom through this link
How to identify VDSL interference v1.0
If you need help with finding your source of RFI contact the EMC helpdesk