The signal might show as good on the map but you might not be getting the speeds as expected. Kindly send us the results of what you have troubleshooted or contact us to troubleshoot with you and send us the results. If the results do show that there's a problem with the signal in your area kindly use the link below to log a query with MTN and give the reference so that we can follow it up. They will install the aerial depending how bad the connectivity is in the area you live in.
The reason why i say you should log a query directly with MTN is because that is the quuickest way to get the issue resolved. Also you are the best person to explain the type of connectivity you are experiencing.
MTN Coverage Nework Query: https://www.mtn.co.za/_LAYOUTS/MTN.SP2010.FormsData/Networkcoveragequery.aspx