Here is what Reg E says about the timing and recrediting of a customer's account who files a complaint. I found this at:
http://www.bankersonline.com/regs/205/205-11.html
(c) Time limits and extent of investigation--(1) Ten-day period. A financial institution shall investigate promptly and, except as otherwise provided in this paragraph (c), shall determine whether an error occurred within 10 business days of receiving a notice of error. The institution shall report the results to the consumer within three business days after completing its investigation. The institution shall correct the error within one business day after determining that an error occurred.
(2) Forty-five day period. If the financial institution is unable to complete its investigation within 10 business days, the institution may take up to 45 days from receipt of a notice of error to investigate and determine whether an error occurred, provided the institution does the following:
(i) Provisionally credits the consumer's account in the amount of the alleged error (including interest where applicable) within 10 business days of receiving the error notice. If the financial institution has a reasonable basis for believing that an unauthorized electronic fund transfer has occurred and the institution has satisfied the requirements of Sec. 205.6(a), the institution may withhold a maximum of $50 from the amount credited. An institution need not provisionally credit the consumer's account if:
(A) The institution requires but does not receive written confirmation within 10 business days of an oral notice of error; or
(B) The alleged error involves an account that is subject to Regulation T (Securities Credit by Brokers and Dealers, 12 CFR part 220);
(ii) Informs the consumer, within two business days after the provisional crediting, of the amount and date of the provisional crediting and gives the consumer full use of the funds during the investigation;
(iii) Corrects the error, if any, within one business day after determining that an error occurred; and
(iv) Reports the results to the consumer within three business days after completing its investigation (including, if applicable, notice that a provisional credit has been made final).
(3) Extension of time periods. The time periods in paragraphs (c)(1) and (c)(2) of this section are extended as follows:
(i) The applicable time is 20 business days in place of 10 business days under paragraphs (c)(1) and (c)(2) of this section if the notice of error involves an electronic fund transfer to or from the account within 30 days after the first deposit to the account was made.
(ii) The applicable time is 90 days in place of 45 days under paragraph (c)(2) of this section, for completing an investigation, if a notice of error involves an electronic fund transfer that:
(A) Was not initiated within a state;
(B) Resulted from a point-of-sale debit card transaction; or
(C) Occurred within 30 days after the first deposit to the account was made.