Murni wrote a letter to Fifi offering to sell her car for RM60,000. The letter reached Fifi on 25th November 2020. Fifi sent her letter of acceptance at 3.00 pm on the same day. Murni later had a second thought and decided to revoke her offer. She tried to contact Fifi by phone at 7.00 am of 26th November 2020 but to of no avail.

On 27th November 2020, Murni went to Fifi's house and informed her that she would like to revoke her offer. Fifi's letter of acceptance reached Murni on 29th November 2020. Murni said that the letter of acceptance was void because she has already revoked her offer. Fifi insists on buying the car and seek for your advice.

Advise Fifi on the legal implications and support your answer with relevant legal authorities and decided cases.