Service tax paid on export services by mistake

Dear All, 

I have paid Service Tax on Export Services (non taxable) by mistake as I was ignorant about the rules. Now I want a refund and do not want adjustment as all my services are export services.

Now I am filling up Form ST 3 for filing Service Tax return. I do not know if I should enter the challan details of the amount paid by mistake. And if were to mention it where should I mention it - advance tax ??

Please advise what to do...Should I enter the details in ST 3 and if I have to where should I enter ? 

Many thanks in advance. 

Best Regards, 

Maharnav