Does the law allows Polish citizens to file RTI against "Urząd do Spraw Cudzoziemców" ?
Yes, you can file a complain against any Poland's office, or even against the President.
In your case you may also challenge the decision which was made - was it the Chief's of the Foreigners Office verdict? Look at this quote:
A foreigner dissatisfied with a decision made by the Voivode has the right to appeal against it to the Director of the Office for Foreigners in Warsaw. The written appeal must be submitted within 14 days of receipt of the decision in question.
A foreigner may also challenge the decision of the Director of the Office for Foreigners in administrative court within 30 days of receipt of the relevant decision.
Note: challenging the decision in administrative court does not legalise the stay. This means that a foreigner who does not have another valid document authorizing the stay in Poland must leave the country.
migrant info pl/temporary-residence-permit-for-family-members-of-a-foreigner-residing-in-poland.html
So several such cases was made by the aggrieved foreigners. But it would be better if you reach for advise from a good lawyer first. Additionally you have to be aware of the costs of such appeal - it's more than 300PLN.
When you want anyway to do this on your own, such documents are required to filling the complain:
- the name of the court to which it is addressed, first name and surname or name the parties, their representatives and proxies,
- indication of the contested decision, court order, any other act or actions,
- name of the authority, of which that complaint concerns,
- determination of violation of law or legal interest,
- enumerate attachments,
(According to: bip.krakow.wsa.gov.pl/59/173/informacje-dodatkowe.html)
The complaint shall be submitted to voivodeship administrative court through the authority whose action or inaction is the subject of the complaint. Of course the case is conducted in Polish.