Tried to submit a medical notification to DVLA (already told them but they want another

) and told to do it online. But to do that you have to sign up to HMG’s
Verify system using either Post Office or another (though the link for the second one wants me to submit on behalf of a company and pay a fee ), so I chose Post Office.
Need 2 documents: Passport (don’t have), photo driving licence, mobile phone contract (which they just call a “mobile contract” so presumably a caravan is OK).
Spent a long time carefully entering all the driver licence details, checked & double checked. Not accepted. Started all over again and still not accepted. Moved on to the “mobile contract”, checked online what details they hold on me (exact address and so on). Not accepted. Did that a second time. Not accepted. I’ve been with them at least 5 years.
Gave up and emailed customer support and got a quick reply “there are many reasons why that could happen”.

.
I expect this is the sort of thing everyone will have to go through to vote etc in future. The only photo HMG photo ID I have is the driving licence and I may soon give that up or have it revoked.