Employment Breach of Contract

Dear Sir,

After I have signed a contract with a company as a Sales Rep, I only worked for them for 2 days. On the 3rd day, I have sent an email, text message and spoke to their HR that I will not continue my employment anymore.I was expecting atleast some training on my first day, but left me all alone to work and I followed up with my commission and did not receive any replies from them. After a week, I have received a letter of Breach of Contract via post mail. Stating that I did not follow the 30 day notice of resignation and have caused them damages already, which I don't know what damages are they talking about. Demanding me to pay 100K in 15 days.What should I do about this? Thank you.

there is indeed a requirement to give 30 day notice, but `100k in damages is too steep

In case, how much is the just amount they can charge me? Should I seek an attorney to reply to the company's letter? or should I ignore it first and just wait if they will send me another letter?
Thank you.

if you can afford to get an attorney, so much the better. there is no legal obligation to reply.