Can't top up

I recently got a contract phone with Telkom where I was given a small amount of airtime SMS and data. So I specifically asked for a top up contract knowing very well their 750 mb won't last.a few weeks later trying to recharge I was not able to, I called the call center and was told I had to go back to the store and pay R400 for something I earlier requested...I am going to cancel my contract it's not worth it...if such can happen in 30 days what else can go wrong in 2 years.