VERY POOR AFTER SALES SERVICE

Ive missed one month payment on my RCS account and then paid it. Now my account with RCS is in arrears even though i have paid my account. I keep on getting sms's and calls from *** stating my account is in arrears but i paid my account. whats the sense of saying i need to make a double payment and after making the payment my account is still in arrears. it doesnt make sense to me.