Mr P installment

I opened a mro account on 21/11/21ade a few purchases, on the 6th Dec I enquire instore about my instalment, the lady informed me i will get a sms with my installment amount. I payed R300 towarda installment on the 6th. On the 9th i got sms installment is R415. I thought i would only have to pay 115 extra to be up to date on installment. I actually had to pay thw whole 415 because aa explained today I made a payment before the 7th. So if you make a payment before the 7th that money does not go towarda installment. I am so dissapointed in mr price. Regret opening account. This sales lady advisee to make payment after 7th caise thwy also only picked this up when people start to complain about payments not reflecting.