Non payment of service tax for the financial year 2014-2015

Hello, I got a letter from Service Tax Deptt. with subject Non payment of service tax for the financial year 2014-2015.

My question is what steps should be taken to resolve the situation? I work as a freelance programmer and receiving payments from abroad for software development services. My accountant says that I don't need service tax registration since its under 'export of services' and exempted from the service tax liability.

The letter says following:

From the relevent records for the finencial year 2014, 2015, it appears that you have earned substantial income but have neither obtained service tax registration, not paid Service Tax thereon.

You are therefore requested to intimate to the undersigned, within 20 days of recipt of this letter, weather the service income earned by you during the above mentioned year is attributable to any of the negative list services contained inSection 66D ibid or is for any reason, exampt from payment of service tax. you are also requested to produce self-certified copy of each of the following documents in respect of the FY 2014 - 2015:-

1. Income tax returned filed by you with the jurisdictional Income tax office.
2. Form 26AS
3. VAT/ Sale tax returns, filed by you with jurisdictional VAT/ Sales authorities;
4. Annual Bank account statements.
5. Contracts/ agreements entered into by you with all persons for provision of service(s)
6. Balance Sheets
7. A reconcillation statemnet of service income reflected in your return filled with Income tax and Vat Authorities. 

Thanks Everyone.