GBS Systems over charged for battery

GBS Systems, Dell's authorised service centre in Chennai, India replaced the battery on my Inspiron 15 5000 (5570) on 2nd January 2025. They did not issue an invoice and also overcharged me. They charged INR 5,900 while the cost of a new battery for that laptop, on Dell's website, was only INR 3,288.87. There has been no response from GBS Systems despite multiple emails. There has also been no response from Dell in spite of several emails and messages on X (Twitter) and Instagram.