the OP had this issue nearly a year ago. I have the same issue - when I
click activate i get a 404 not found page. Does that mean this known
issue is taking a year to fix? O2 need to look for some better
developers if that's the case
The only reason we went with O2 was this offer. July 2022 and the same
issue is occurring for me. Any positive marketing effect O2 expect from
this offer is negated by the fact that it doesn't work, leaving me less
likely to use O2 for my other phone...