(tested in htc desire)
Go to the stock dialer and type: *#*#4636#*#*
Then go to the Phone Information -> Change Set Preferred Network Type to: ‘GSM Auto (PRL)’.
Then Press Update. Wait for the radio – 1-2 minutes
Then press Menu (hard button), choose Select Radio Band, choose Euro Band. Wait for another 1-2 min.
Then reboot the phone.