Sending phone in for repairs

I have handed in my Huawei G7 for repairs due to the device not charging. When handing the phone in the screen guard was cracked, however the lcd display was fine before sending it in. Phone is not even 3 months old now the warrantee is not valid anymore because apparently the screen is cracked? The support and help you get from the repair centre is pathetic and C Surance not much help either! They either drop the phone on your or they can't even get your details correct on the system. Now i have to pay for something that is not even the problem. I have had endless issues with Cell C and i am ready to cancel my contracts with them and go to somebody else really!