Poor service at MTN

I received a call from MTN agent selling me a cellphone deal but wanted a Router deal. So I took a portable 17 gigabyte day & 17 gigabyte night. I then recieved my router within a short space of time & used it. Now after a month I saw it not connecting & I phone MTN, they told me that my data bundles are finished because in their system it shows that I took a 5 gigabyte deal. I then told then what deal I took. She then escalated my query via email. I then recieved an email telling me that the agent made a mistake and captured a wrong deal they will correct that. No response I have received yet. Its been a 6th day now & I have to buy data bundles because I need them, yet they will debit my account with the 17 gigabyte deal not the 5 gigabyte that shows in their system.