I have a similar issue - I can’t apply a sky sports month voucher online. After chatting online (eventually) I was just advised that it’s a known issue that’s been worked on. There is no eta for resolution, so it looks like I’m missing out big time on the football today!! Very disappointed to say the least. I was advised that I’d be emailed once resolved and to keep checking the online community meantime. I have bought another voucher for a family member for Xmas too, so hopefully we don’t need to go through all this again!