I have been paying Mr price religiously for over a year

I have been paying Mr price religiously for over a year. The last payment I made was at sheet street on the 7th of July, and opted for the receipt to be emailed. Weeks went by without receiving my proof of payment, I then called them last week and they reassured me that everything was sorted and that the payment is reflecting. I check my credit score today and it went down by 24 points due to “missed payment”. I need this to be sorted out and the correct information be sent out to credit bereau because this is having a negative impact on my profile