Catch 22. My wifes mobile had a fault and the screen said “unregistered phone” I took it to a local guy who has a stall next to tesco. He said that the sim card was corrupted and flogged me a new sim card for a £1 with the advice buy a top up card from tesco. I did that and the phone rang in ok. Tried to put the £10 voucher from tesco on the phone using 150 and 146. All I got was a pre recorded message saying because I had no credit icould not talk to them.
Also on the phone before the corrupt sim card there was £8.60 credit.
T Mobile now have £18.60 of my money and I have sod all.