Rizwan Ali “had been” in Islamabad since the first of this month and does not intend to leave for London until his sister arrives.

Explanation
Rizwan Ali "had been" in Islamabad since the first of this month and does not intend to leave for London until his sister arrives. eliminates an error in the sentence Rizwan Ali "has been" in Islamabad since the first of this month and does not intend to leave for London until his sister arrives. ضوان علی اس ماہ کی پہلی تاریخ سے اسلام آباد میں ہیں اور اپنی بہن کے آنے تک لندن روانہ ہونے کا ارادہ نہیں رکھتے۔ **** “has been” is used to mean that something began in the past and has lasted into the present time. such as "Rizwan was already in Islamabad and they stay her "  so " has been" is best to make a meaningful sentence   ND16-8-2023