The company which paid you the fees must have not made provision for the fees payable to you in each of the earlier years. So, now they have debited Rs 75000/- to p& L a/c .They have to deduct tax at source.
But if you have shown the earlier fees (Rs 50000) receivable in earlier years and paid tax on that, you don't have to offer it to tax again now and can claim the entire TDS.
Some professionals usually maintain their accounts on cash basis and tax the income on receipt basis. If you have done so, it would be beneficial for you when TDs is deducted in the year of payment.