LG Electronics — refrigerator/invoice not received

Address:

Pune, Maharashtra, 411013

My Father Jeffrey Fleming contacted the service center directly as his fridge was not working. The service center sent a technician on Monday 16th July to inspect the fridge and told my father Mr Jeffrey Fleming that a gas change will be needed and would cost Rs 4600 which was done and an invoice would be provided via email which till today, Sat 21st we have not received. We were also told there will be a 5 year warranty which we cannot claim if required without the receipt.
To solve this query we need to know if the amount of Rs 4600 charged is correct. It sounds like an over charge for just a gas change and also we need the online receipt that was promised.