Installment *******

I have an edgars account that I pay every month. My installment is usually between R250 and R280 never more. This month I received an sms that I must pay R527 wich I have a 12 months plan and I haven't purchased anything. This is a complete ******* and I will not pay that amount only my installment and I will take this matter further if they don't fix this before I have to pay my account by the 26th. If they want to make contact they can just email me.