Voda have lost it - sadly
I've just switched to EE after 20 years with Vodafone.
Last year Voda did some sort of major systems upgrade (Oracle I suspect from the error messages at the time) that resulted in numerous (based on Voda's own forum) customers being orphaned by the billing system. So you are paying on direct debit, receiving a service but you can't get a monthly bill because 'your account isn't set up'. For 9 months I worked with Voda to get the issue resolved - speaking to help desks in Ireland, UK, Egypt and India - escalated to the highest technical authorities and was eventually told it was 'unfixable'. And Voda advised that even if I took a new number the error would still present itself because the database that contains the customer info is screwed. Hard to believe for such a company.
So with a heavy heart I switched to EE with a new number (Voda were so messed up they couldn't produce a PAC), notifying the contacts is easy - fixing all the sites that use 2 FA, less so. The best bit of EE is that the call centres are in UK and Ireland, sensible people who go out of their way to get it fixed.