Which of the following is not impermissible collector contact under the Fair Debt Collection Practice Act?
A. contacting the debtor at inconvenient times or at inconvenient places
B. contacting the debtor once the debtor has asked the creditor not to call
C. contacting the debtor once the debtor gives written notice of refusal to pay the debt
D. contacting the debtor once the debtor informs the collector of attorney representation