Rain internet services provide

I have cancelled my rain in march i have paid them 958 in april course i had 2 wifi so now i have one wifi which is my mothers it showed me that i must pay 480 so i pay on the 15 of every month so this morning when i wanted to pay them it showed me 958 which i dont understand course i paid them end of april so when i email them there are telling me i must pay 958 which is wrong and what is worse you cnt even call them you just have to email them they network is like **** half the time it doesnt work please help