@Kapil Chandna: you were advised to not venture into business promotion while answering queries here, if you cannot answer do not canvas business, it is unethical and irritates others who spare and devote their valuable time to render service at free of cost.
@Querist: If the purchaser has paid the taxable amount on your behalf, it becomes your duty to return the same to him, however, you may consult your auditor/Chartered account for a further opinion and proceed as per his advise, in my opinion, it should have been suffered by you.