I've found that this service has hardly worked at all over the past few weeks and have actually started randomly checking the service quite regularly every day and find it's unavailable far more often than available.
At present if I txt bal to 777 I get a reply saying "sorry unable to process your request at present please try again later". I also get the same response if I go to the 777 IVR and request a balance. Sometimes the TXT service works and the IVR fails, sometimes the IVR works and TXT service fails. These problems all seem to have started once the MYA web service started showing a correct balance around 10 days ago.
What's up Vodafone? What sort of service are you running when people are unable to get an accurate balance? It's taken over 3 months to get the web based service working and even when the TXT service does work it still dosn't tell me my offpeak minutes or data balance.