A cry for help!

My wife was in the central North Island over the weekend, and was roaming on Vodafone with her 2Degrees SIM/Android Smartphone.

She found that she wasn't able to send SMS messages; but could receive them fine.  Unfortunately due to the marginal coverage where she was staying, she didn't get very far with 2Degrees help line.

Now she's home, I've had a look at the phone, and it looks like the SMSC settings are wrong.

On the 2Degrees website, the Text delays or issues page talks about dialling "*#*#4636#*#*", then going into "Phone Information", and checking the "SMSC" settings.  Apparently it should be "+64220227672,145"; but on her phone when I check "refresh" it says "0791462207276f2".

Unfortunately, the next instruction on the website says enter the correct number and click "Update"; but when I do that, it doesn't seem to do anything, and pressing "refresh" again just returns the original "079146...." number.

Note that in the actual Messaging App, the "Message centre" number does look right (i.e. +64220227672); but as it wasn't working, I'm not sure if that means anything, and I'm only going on what the 2Degrees help website says. 

At any rate, any wisdom out there on what to do next?  Or will we need to go into a store and try for a SIM swap?

(Samsung GT-S7500, Android 2.3.6)