Currently MTN has been working on improving their network country wide. Once they have completed the project for iproving the network you should be able to see some imrovements. If what they are currently implementing does not improve your mobile connectivity 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 will assist you further with regards to aerials, equipment, line of sight etc.
I hope this answers your questions. If not please elaborate more so that i can answer correctly.
MTN Coverage Nework Query: https://www.mtn.co.za/_LAYOUTS/MTN.SP2010.FormsData/Networkcoveragequery.aspx