About confirmation to builder on encashing of post dated cheques

Hi, My friend had purchased a flat in 2013. However due to lack of funds the builder hasnt started the project. We cancelled the flat one year back in 2015. So we are expecting the amount paid (roughly 25% of the flat cost). We have been consistently been after the builder for the refund of our funds. He has now finally issued 3 post dated cheques for 3 months. However when issuing the cheques he wanted us to sign a letter which stated that 'we should confirm from him before depositing the cheque'. My question to all you respected people is, Is this allowed in first place? If he is issuing PDCs can he put such a condition? Doesnt this give him a right to keep postponing the deposits whenever people ask him for deposit confirmation? Also, even if he takes this in writing on a simple paper, if he says not to go ahead with the deposit but we still go ahead and deposit the cheque and it bounces, can it be considered under section 138? Appreciate your responses. Apologies for any typos. Thanks