Poor Service

I bought a data package with MTN which costs me R 1000 a month, over the first few months, it was fantastic, but now over the last couple months, the speed has been terrible, from getting up to 30mb/s to now getting less than 1mb/s. I have contacted customer support and they have just told me that the batteries at the tower were ****** and they have no intention of fixing it. There customer support is terrible, they have no regard to helping a customer but to rather take the money and carry on. I require a good speed as I work from home and I have a nanny which I connect to the wifi so that she is able to communicate with me, should I leave the house to see a client.