PayJustNow is treating customer unfairly not happy at all😔

Good day I would like to get help regarding the laybye I did with PayJustNow as I'm currently not happy to what I'm experiencing now as is not what I agreed upon was told would pay the laybye in 3 months by the 1st and it's interest free but now I see am being charged more than 100 which is almost half of the instalment payment did try to call them yesterday upon while was busy with the payment and went to voicemail/answering machine and e-mailed them this morning but no respond till now as I have received a text in the early mornings of yesterday 03:40 if payment was not done by yesterday will be charged more which is interest of which I was not even aware of the late payment will be charged more what I was told you pay in 3 months take the item with you and it's interest free the difference with the normal laybye you deposit 10% and get the items once the laybye is paid in full with PayJustNow you deposit 30% of the total cost of your balance with the card and take the items with you on point of sale and pay in 2 months after your 1st instalment and pay by the 1st of every month not even being explained if payment is late by the next day which is the 2nd will be charged more it's not fair if that wasn't clarified even on the sms or emails I have received nothing said so now I must pay 450 something instead of 333 within 1 day of late payment of something you were not even aware of it's not fair.