Poor customer service

We handed in a Samsung S7 to have the screen replaced because it's still in the first year the screen is free. After 2 weeks I received an SMS"Good day, Your device has been returned from the Vodacom Repair Hub. Kindly provide your job number upon collection. Regards, Vodacom Blue Route ********** 188" only to find that absolutely nothing has been done to the phone. The consultant was as shocked whilst unwrapping the phone. Then she showed us a comment noted on the job card that the device has been "blacklisted ". There is no way the device is blacklisted whilst booking the device in we were requested to provide proof of purchase which we did. I tried calling the store about 15 times today the phone just rings. Not impressed at all.