Complaint Review: Sprint

I lost my phone and reported it stolen to Sprint wireless. Since I had insurance, sprint provided me with the contact info for me to get a replacement phone. Everything went well, and I received a new phone. about a week later, I looked at my bill and realized that whomever found my phone, made about $80 worth of long distance calls with my lost phone. I called Sprint to have the charges removed but they said that I was liable for those charges. Sprint said that I did not request for them to suspend my account while I waited for a new phone. Why do I have to tell them to suspend my account?? Isn't calling in to report a lost phone enough??? Shouldn't they do it automatically when a customer calls in to report a lost phone?