Blackberry bold 9700 o2 must see minor fault .

Blackberry bold on the o2 network its not blocked i gurantee that however when i am calling someone the phone freezes and turns off. You can send texts etc...However when using some programs i,e, forwarding videos or making calls the phone freezes and turns off then restarts again and until you make a call it dont turn off. This may be a little minor problem...I provide a charger with it only...Also the camera does not work for some reason i am being as honest as possible it may need a hardware upgrade from what i see as i write the problem on google... Need it gone asap OFFERS... Call or text on 07900334459