Disappointed with the payment process

I am very dissapointed with the online payment system of CAO. I was applying for my sister and made payment on her behalf more more than a week I am still receiving emails saying the payment was not received. Their website has an option to pay instantly and that was the option I used, why have that option if it does not work. Everytime I call they tell me that I need to send a proof of payment which I have emailed to them a number of times. This is very fustrating, as it seems like CAO is not willing tio assist. I just wish it was possible to apply directly to the universities because this is not working