Reliance Digital - Product sold without bill and product return not respected

I have purchased a product UBL *.* speaker on **th Dec.****. I'm attaching the bill for the same, the service guy came for installation of the device insisted that the product needs a stabilizer - which he had brought it along with him. The stabilizer socket doesn't fit in properly and hence I asked for the return or a better stabilizer in return. The person promised that the bill would be delivered to email but they haven't inspite of multiple reminders. The Relaince digital store is in HSR Layout, the service guys name is Syed, store manager is Nagraj. The resolution I expect is the return of the stabilizer.