Am I entitled to claim compensation for the delay in completing an agreed-upon work, and for the period my money remained with the other party without completion, or must I pay the additional amount he is demanding after the increase in area?

This contract falls under the permissible manufacturing contract (Istisna') provided that the type and specifications of the manufactured item are clearly stated, and the deadline is specified. It is permissible to defer the entire payment or pay it in installments. It is also permissible to stipulate a penalty clause in the original contract or in a subsequent agreement. The questioner had the right to demand that the workshop owner complete the work on time, but his failure to annul the contract and his acceptance of the current situation means that he cannot compel the workshop owner to compensate him for the delay period. The down payment is part of the total price, and no compensation can be requested for it remaining in the workshop owner's possession. The increase requested by the workshop owner is not binding on the questioner unless the contract stipulates it or the questioner authorized an addition that entails extra cost. It is advisable to adhere to the contract and reconcile between the two parties.