Telkom mobile got worst reception of all time

In September 2014, I took out a iPhone 5S contract from Telkom Mobile but since then I've been struggling to get reception, everyday I get that people that try to get hold of me but my cellphone seem to be off because of the bad reception. And I get a message from my voice mail someone tried to phoned me.<br> <br> I pay for a service and telkom mobile does not deliver a service to me, if the problem can't be solved, I want to cancel the contract!!!