Threatening sms

I've received this sms this morning Due to non payment, we are forced to suspend your Tracker account. This may impact both your insurance policy and your credit profile'. <br> <br> I called your accounts department as was shocked, knowing that my subscription has been paid. The outstanding amount is that of a call out fee, your technician fitted a tracker in October (which is this month by the way) <br> <br> If you guys so desperately want your R550 call out fee kindly do it in a professional and ethical manner. Don't threaten me via SMS, that just unacceptable. <br> <br> I've been with Skytrax for +4 years don't force me to cancel my subscription <br> <br> Can someone call me to resolve this