Poor customer service from Momentum & Platinum repairs

I lodged a claim for my broken phone with Momentum Insurance and I was given claim number and I was immediately told that their service provider will contact me to arrange for the assessment and repairs. By this time I was told to download and remove all my information from the phone because they won't be held responsible for the loss of info due to repairs. I took my phone to my usual cell phone repairer to help me with that. Their service provider who is Platinum Repairs contacted me to arrange for the assessment/repairs for the phone. We made appointment for this Friday 9am. To my surprise I got an invoice for the repairs which wasn't done yet but to be done by Friday. I called and spoke to the lady from Platinum Repairs who told me to deposit the money which is mentioned on their invoice. When I asked why do I pay upfront for something that isn't repaired yet, she told me that they're not allowed to send their technician to assess before paying. I went back to Momentum and explained it to the other guy who promised to call me today in the morning and he didn't. I then called Samela who is my consultant who helped me initially and he called Platinum Repairs and told me that they misunderstood me. Then I told her sincewhell my phone is with my usual repairer can't they assess it and carry on with repair and then Momentum can pay. Samela told me that I'm not allowed to use my own service provider because they might not pay them. I then asked if I'm forced to use their unreliable service provider (Platinum), she then told me that she will check on the policy wording and send me that clause. She then changed and said that I must tell my Phone repairer to send them damage report which I did. I tried calling Samela today to no avail and also left messages for her at her colleagues but she never returned to me nor acknowledged receiving the mail concerning the report. I'm loyal customer to Momentum and phone is my work because I can't perform my duties without it. Please help as this is very urgent.