Mobile installation file is used for installing cracked apps.Read the rules&you will see any warez&crack not be allowed on this forum.So don't ask about it.Just search it on google...
Can't imagine it's the Mobile Installation file that has caused the change. Are your settings on the phone still showing the UK? (ie Time Zone etc). I know I've had to reset mine everytime I've done an upgrade. Also what about when you access the iTunes Store via your computer or iTunes on the phone?