@Powell70 Hi there, unfortunately not all O2 Open companies are able to be verified via email, even though it may give you the option to do so (very frustrating!) as the website is only preprogrammed to accept certain types of email address, e.g. @gov.uk for government and not all will work.
I understand it may be hard to obtain a wage slip, although it will accept them up to 3 months old if you had a previous one to hand. There is typically a 28 day timeframe to add your discount (which will not effect your next bill anyway), but I’m sure in these exceptional circumstances they may be able to make an allowance and add the discount on later for you. The people to talk to about this would be customer services, although they are experiencing extended waiting times at present. Would be worth a ring to see if there’s anything they can do for you.
I work for O2 but my comments and opinions posted here are solely my own and do not reflect those of Telefonica.