MTN IS HOLDING MY PHONE HOSTAGE!!!

I booked in my phone approx 2 weeks ago with MTN East Rand Mall. My iPhone 5C had a software glitch which was not coming right. It also was not finding a signal propperly. I told the consultant at the branch that the phone is insured and that if it came to it I will claim to have it repaired. This was done all fine. I then got an sms to say my phone needs repairs because of \Liquid Damage"(My phone never ever ever ever got wet.. not ever) My Job number is ***. The cost would be R3364.73 This was obviously a rediculous ammount to quote on a repair regardless and I still question the integrity of the repair department concerning. I then phoned my insurance (24hr Mobility) which is to my knowledge a MTN insurance company. They told me to get the handset back"