Bismihi ta'ala
It is very sad that at times of divorce the Quranic method of dealing with it is not observed. The holy Quran says in Surah al-Baqarah, verse 229, 'tasrih bi ihsan', which means to part ways with "grace".
Unfortunately, we can sometime see that for whatever reason the husband, his family, or at times the wife and her family wish to forget any good and pursue not only to oppress their spouse, but to become vengeful and spiteful towards them. One way of doing this is through money, or for the husband to misuse his authority by withholding from divorce until he gets what he wants.
In this case it is gifts.
It is not just an issue of it being permissible for the husband to demand gifts, or refuse to give back what he owes. If he has such a state of mind, then unfortunately he is not interest in doing good or being graceful, and he would not care if he is doing dhulm.
If you are in an Islamic country, with an Islamic judiciary system, then you can pursue this by the Islamic courts.
If you are not in an Islamic country, you need to weigh out the situation and try as much as you can not to allow the husband to keep you in limbo and not grant the shar'i divorce.
If family negotiations are to no avail, you should think of the option of mediating a qualified religious scholar who might be able to convince him of how to deal with this in a righteous and noble way.
If the husband refuses to cooperate, demanding the return of the gifts and refusing the pay back owing money, then if it is within your ability to hand them over, in return for your shar'i divorce, then that would be an easy way to bring this to an end.
If what he is demanding is beyond your capacity, or the husband changes his mid, or anything else, then the next step is for you to contact a religious authority.
With prayers for your success.
