Unpaid claim

I have insured my phone with them June 2016 and since then i've been using my prepaid number. last week Thursday i was ****** and i submitted mu insurance claim and they told me i was supposed to be using the contract number and the claim was declined. My question is: Using the contract number was going to stop the goons on taking my phone? Why all this time they never tell me to use the contract phone and alert me of the consequences of using another number.