my tablet has a huge crack on the screen!

I took my tablet on contract last year may(samsung tab3 10.1) for academic purposes,in december for the first time i took it for repairs as it was switching itself on and off.when i got there we assessed my phone and the consultant told me it was just short battery life,it had a screen protector and just dents from falling accidents.they charged me R816 and mind that i have insurance they only told me afterwards that i was supposed to contact my insurance company (CALL GUARD) okay i told them they can give me the phone back so that i can call the insurance and when my tablet came back it had a huge crack from one corner to another i then explain and showed them the assessment copy that my phone didnt have a crack wen i gave it to them and it was around february they promised to talk to the supervisor Faith and they didnt get back to me last month they told me the person who assessed my phone no longer works for mtn.right now i havent heard anything from them and they are still deducting the money monthly.i fear that with such a huge crack even if they fix it it will give me a lot of problems in future because it must have fell really hard.dont i deserve a new phone?please help