the police would not be interested.
not going into details but i was once confronted by a youth with a knife, so right in front of him i called 999 on my mobile, was put through to the police who took a description, i said that the offender was standing right in front of me now, they said someone would be there as soon as possible, offender ran off, 1 hour later no police, and no follow up call ever made.
i could have been killed.
best thing to do... IF YOU REALLY WANT TO SORT SOMETHING OUT... diy... but you do a crime, be prepared to do the time. if not walk away.