What is the ruling concerning a girl who used to talk to young men and ask them to top up her phone credit under the pretext of a birthday gift before her repentance?

The girl who engaged in an illicit relationship with foreign young men and received phone credit from them must repent to Allah with sincere repentance, by abandoning the sin, regretting it, and resolving not to return to it. She is not obliged to return the phone credit given to her.