Sec 40 a (3) or 269 ss/269 t

(a) My client is engaged in the business of vehicle dealership. It received an amount from a customer towards a vehicle through bank at the time of booking. Later on after some discounts and scheme adjustments, the dealer have to repay the excess amount to customer. Can this amount be paid by cash if it exceeds Rs. 20,000? 

(b) In case, if the dealer purchased used vehicle from that customer, will the repayment attract Sec 40 A(3)?