Complaint on a pathetic service received.

I bought a Mobicel tablet on the 20 July 2017 at an MTN oulet in 5 Simmonds street. 3 months later i took it back to the store as it wasnt working. Since October I've been making follow ups on the table and each time I get told different stories, one minute it is still with the warehouse and the next they cant locate it. I received a call from mtn 5 simmonds street advising me that the device is ready for collection after 4 months of struggle. I went there on Monday to collect it, thr tablet was still nit fixed. They seem not to even know what the problem was with the tablet and they only asked me then. I am so disgusted with the service, how do you keep my tablet for 4 months and tell me it's fixed where else you didn't even note down what the problem was with it. I brought the tablet before the end of school term last year now its the begining of the term my child is affected by this incompetency of mtn. The device was mainly bought for school use. I feel like I've been patient enough and now I'm disgusted with this whole incompetency and non proffessionalm by the staff of mtn. I left the tablet yesterday and they promised tp call me back to come fetch it as they were still looking at it. I haven't reveived a call from them to date. What do I need to do though with such service. One word to describe how I feel about mtn "Disgusting". Like