No feedback and pathetic customer service

I recently lost my phone and I use it for business and I really need a new device my upgrade date is on the 05/07/2018 I'm am willing pay for may and june my installment and can you push my upgrade to may as I'm in dire need of a new phone please can you help me. I've tried 2 times to get into contact with the retentions department each call of 25 and 34 mins each with no one answering from retentions after they've transferred me again I tried again today and still no one from retentions has helped me and I even sent an email as well still no feedback. URGENT ASSISTANT IS REQUIRED