blacklisted my prepaid handset

received a call from the manager threatening to blacklist my prepaid handset as I could not give information on ex collegue , I told her that I did not have any details or contact and the outcome of the situation is that she blacklisted my prepaid handset , she told me to send my proof of purchase to prove its mine , I think that was very unprofessional first of all , because this handset is mine I bought it cash and no one has the right to interfere with it , now she has inconvenienced me as I cant do my work as I use that handset for business and no other alternative phone