Pest control

I booked an APC Pest Control service in Mira Road for a bedbug infestation about two months ago. Before booking, I spoke to them over the phone, and they told me that one session would cost ₹600 and that I would need three sessions in total to completely get rid of the bedbugs. The next day, their representative came and only sprayed some chemical superficially on the bed. He did not carry out the proper pest-control treatment that was promised. He then collected the entire payment for all three sessions at once and left. It has now been two months, and the bedbug problem has not been properly resolved. Moreover, they are neither answering our calls nor responding to our messages. They also sent us a receipt via WhatsApp, but the receipt does not have any company stamp or signature. We want to file a complaint/case against this company for providing inadequate service, taking full payment in advance, and then refusing to respond or provide the promised service. Please guide us on the appropriate legal action we can take and the documents/evidence required to file a complaint.