Non Responsive Call Centre Agents!!

Three weeks ago (17 Nov 2017) I called Momentum with a query on my Multiply account - the call center agent said she would escalate my query and Momentum would contact me with a response - to date (04 December 2017) I still haven't received feedback. She said it would take roughly 3 business days before I get a response. Last week I sent an online query via the Momentum website and still no response. I've tried calling the call centre today (16:55) and was on hold for the next available consultant indefinitely. The message that played over and over again was "We are inundated with calls, please hold for the next available agent". Does Momentum ever call clients back as promised? I've been with Momentum for almost 4 years and not once did I put my payments on hold or promise to pay and never delivered.