Utterly disgusted by this company

I am so shocked and disgusted by the way Mr Price works. What a *******!!! I recently opened an account with them but the interest rates did not make sense to me. I was short on one payment because apparently the interest changes and so does the installment. Okay that was fine so arrangements were made with the call centre to make payments which I called to arrange, from there I have been harrassed and threatened with defaults just after arrangements are made. When I told them I would pay the full amount they would only ask what I can afford and it would be fine, I don't have to pay the full amount. After weeks of getting endless messages I decided to pay off the account. I called Mr Price to arrange it and also made sure to find out what the amount will be. On the 14th of December at 13.29 I received an SMS reminding me that I agreed to pay the full amount of R3818 by the 25th. Today I have to pay R200 MORE. This company is a total *******. I have other accounts and have never experienced such bull****.