Your father says absolutely right because when you have completed your summer vacations homework, he would fulfill your demands and wishes. How can you complete it, it is very easy. You schedule it in such a way that no one could bother you. The best time to do that is just after Salat al Fajar. After Salah you perform some daily exercise and have a glass of fruit juice, sit for a long time to complete the homework. Make schedule and try it from tomorrow. Insha Allah you will feel the difference in you.