Reliance Trends — charged for carry bag from the store

Address:

Reliance trends goyal towers, plot no 5-6 tiwari colony hanumangarh junction, town road, Hanumangarh, Rajasthan

We made a purchase of nearly rs 5000/ from reliance trends store in hanumangarh junction. The store charged us rs 7/ for carry bag. The item has been billed. It is such a illegal practice to charge for carry bag even after making such a big purchase. How justified is this? It has been stated as per ministry of environment that only for plastic bag a customer can be charged that too for environment reasons.