Yea, in 5.2 there are tags for the added numbers. Also, you can edit the country code freely in that version...
I'm scared to try new versions of Skype each time..
To edit phone numbers, open the contact, then hit the down arrow near "call" button and move your mouse over the phone number you want to edit. The number will be colored with blue, on the right side you will notice a pen, if you click it, you can edit the number.
This works for numbers you've assigned to a contact.
In version 5.8 (and possibly before), you can select the contact you want to edit, and click on the little arrow next to "Call Mobile" (or "Call ...."). Move your mouse to the number you would like to change, and choose the little pen next to it (the pen will be there only when you move you mouse on top of that number).
Once you select the pen, you should be able to change the number.
so glad to have read all of these problems about simply editing a phone number. I thought I was being stupid. Does sound likea real glitch. And kind of a silly one in this day and age.