My sister works for the NHS and got a 30% off refresh tariff code which she could share. I applied it via text and received a tex back saying it had been applie to my account. When I look in my account where the bolton things are t says 30% o2 open but my bill still says the same. It's a new upgrade so I haven't actually paid a bill yet but I just assumed the discount would show. I have the £17 contract and it still says the same £17 refresh and £15 for the phone = £32 a month.
