MTN reception for voice and data appalling

I have been having issues with MTN cellphone reception in my area for about a year now. I have called MTN and reported the problem on more than one occasion and every time they tell me nothing is wrong yet I have tried 4 different devices and still get terribly poor reception. At most I get two bars but usually only one. People are unable to hear me speak as voice cuts out often. Data is so bad that I can't make VoIP calls or browse the internet. Latency on data sits at around 800ms which is shocking to say the least. This problem hasn't always existed and from what I can remember it started about a year ago. Hopefully someone from MTN will read this and at least attempt to assist. At this point I'm sorry I renewed my contract which I've had for more than 10 years.