demanding my iphone 13 back

i recently odered an iphone online from mtn and the agent that was helping me did not do an insurance for the phone that i bought whereas on the contract papers i clearly indicated that i wanted a insurance and signed on it. now that my phone has been ****** he is telling me that there was no insurance made on the phone and i cann not get a new phone now ..ive been sending emails am not getting any feed back its been 3 moths now