Very bad service

2 months ago i went to Mr Price Upington to change my acc from 6 months to 12 months (reason been i could not affort the installment of 6 months) the lady at the tillpoint told me that it is going to take 30 days to change it, i agreed with her, that very same day i payed my 6 month installment, 30 days after my complaint the told me i must pay another 6 month installment, I went to the store to ask about my arrangement i did not get answers so i payed my acc on 12 months, today the phoned me to tell me i must pay R1575, Mr Price is a fly by knight company i cursed the day i oppend an acc with them.