Welcome to Vodafone Community
Finally received a "Master Code" today after nearly 6 weeks of trying. Luckily I managed to get my device unlocked for £10 and through the complaints process got this refunded as well as the cost of not being able to use my new sim provider although I was paying for a new contract, and also the cost of staying with Vodafone for an extra month. Unfortunately I won't know if that "Master Code" will actually work as I don't want to risk anything now that I've paid to have it unlocked privately. So the elusice "Master Code" does exist, can Vodafone staff actually be trained to recognise those words and stop denying it doesn't exist!
I've also had exactly the same problem having requested a NUC for a Vodafone Samsung in mid September to put in a USA SIM card for the end of October to use while on holiday. The phone requests a PUK rather than a NUC and in that 6 weeks, I have spent hours on the phone with Vodafone Technical Services trying to resolve it and have had multiple emails telling me that they are on the case with the Resolution Centre.
About 5 days before I was due to leave I phoned again saying it was getting urgent, I was told that I would have an answer within 24-48 hours, 3 days passed and nothing heard, so I phoned again and received the same answer, it will be 24-48 hours. I went to the USA carrying this deadweight phone hoping for an answer which arrived 2 weeks later, the same day I returned from the USA. This triumphant declaration came up with the same NUC that I had received back in September and which I walked through with the Technical Services multiple times.
This whole process has been a complete shambles from start to finish. I needed an unlocked phone to use for administrative purposes and in case of emergency while I was touring the USA. I'd relied on Vodafone to come up with a solution and was let down badly. Fortunately, a friend in the USA gave me his old mobile and T-Mobile in the USA sorted the porting of my temporary SIM card and NUC for his phone in less than 2 minutes. What a contrast.