Phone ****** from repairs

This company has been failing to return the phone i had sent in to MTN for repairs for 3 months! WHAT MORE MUST I DO? i can not keep calling, emailing, and visiting stores to just get a no as an answer. What about my expenses? my debit order that goes off on time for a phone i do not even have! the amount of chaos that has erupted in my personal life because of my lack of contact has cost me multiple opportunities and offers. At this point, what is the point?