MTN contracts useless - communication stops abruptly

I am writing this on behalf of a small business owner.

They have signed up with MTN for two contracts, both contracts have the same issue. When someone phones them or when they phone someone, the communication stops abruptly, THIS IS NOT A SIGNAL PROBLEM, both phones do the same when they are in a city like JHB, East London etc, it happens all the time, everywhere - brand new phones.

They went back to the store they signed the contracts with, within 5 days, the store then said they will fix this issue, which they couldn't.

So it's been 2 months, they have lost countless business because of this pathetic service and no one could care at MTN.

I expect a regional manager to contact me, please do not give this to a sales rep, we are past this.