where is my phone

I sent my broken phone back to assurance in the envelope provided. Some how it got lost? And I got charged because they never received it. Why am I getting charged if I sent it. I called they said I will get my money back in 2 to 3 bill cycles. It's been almost 4 months now and Everytime I call they don't know what to tell me. That they are still waiting. They are going to send a email to the higher ups. They went to check the inventory see if it arrived. This isn't fair.