Blackberry 9720

i have had endless issues with my Blackberry 9720. <br> i have sent the phone in 3 times to be repaired (twice in the last week) and everytime it comes back, it has the same rebooting issue. this apparently is a common issue with the 9720's - according to the consultant who helped me at the above branch told me that sending it in for repairs isnt going to fix the issue. <br> i asked another consultant if i could replace the cellphone with one that works or end my contract early and i was told no. so my question is?? do i keep sending this phone in for repairs once a week? or will i be given another cellphone? or can i upgrade early? no one seems to want to help me. seems like the service i am paying for isnt being delivered!