Reception Issue

I have a Telkom LTE internet contract which I am very happy with. Because of the low pricing of data and the very good speeds I am getting, I decided to buy myself a Telkom prepaid SIM card which I am using inside a Samsung Galaxy S4 LTE phone. The whole idea was to get myself a mobile contract after using the prepaid service for a few months. My problem is that, although the reception goes all the way up to HSDPA+ the connection drops the whole time in such a manner that I completely loose reception before I get chance to download anything. I contacted the help desk and was told to roam on MTN. Now I have constant reception but it is so slow that I can't download any attachments from social networking apps or even browse the internet. The weird thing is that my home Telkom internet is running fine. Then I have also noticed that roaming on other networks costs more. So what is the whole point of using Telkom for my mobile then. Since my Telkom home internet is fine, roaming on another network is simply not a good enough solution or answer for me.