I ask the question to motorola. and they replied as following.
Thank you for contacting Motorola.
Unfortunately we must inform you that your phone is out of warranty due to tampering with the software. To regain the UK software you have two options, try to perform a software update, if this does not work, you will need to send your Dext to the repair centre where it will be re-flashed with the UK software. You will have to pay for this service, please contact the repair centre for a quote on 0871200995.
For any further assistance or information please do not hesitate to contact us again, quoting your Customer Reference number.
Thank you for allowing us to be of service to you.
Motorola Mobile Devices Contact