If your Desire is synced to Facebook contacts and some of your numbers are going crazy, I found this simple solution and it seems to work. I have a contact with a mobile number of 070000000 (You get the idea) Now if that person has entered there number on facebook, they add the country code so the number becomes 4470000000. When the accounts are linked together, the facebook number takes priority. Try to ring this and the number fails as it is not a valid number. After playing around, i have found a way to fix it (yay i here you all say) Click on Phone Find a contact with a incorrect number (as mentioned starts 44) Long press on the contact Then click View contact Scroll down and press edit Change the mobile (This should have the proper contact number in it) to another option (Fax for example) Click Save Long press on the changed option above(Fax) and select "Set as primary number" Select edit again Change the Fax option back to mobile and click save. This will make the proper number the default again rather than the facebook number.
I found another way to change this, its faster. go to people on your htc desire, then click on the contact giving you problems, then you will see the number at the top with out the +, hold click on that number then click edit, (HOLD CLICK ON THE NUMBER ITS SELF) then put in the + in the front of the number then click save. sorted it out for me one time!!!
This is well documented on other forums (and I'm sure it's on here too). Is the best way of doing it but why Facebook can't just update it their end I don't know
