Fraud on the name of getting work visa

Respected sir/Madam, I am residing in Mulund Mumbai. I was supposed to send one carer for old lady in uk for my friend. That maid asked me to seek help of a dental doctor with whom her sister is working as full time house help. Doctor said he has good connection in embassy with some IAS officer so work visa will be done sureshot. That too in maximum 20 days. We repeatedly asked him if it's official or no. He assured me that everything is going to be official and for that I hv to pay him 3.5 lac . And if the visa is not done then full amount will be refunded back. Because the transfer he was asking was online and not cash we relied on him and transferred money online. But we had no clue what was happening through out. We kept on asking what's happening with the procedure. He always used to reply that it's under process and finally that maid withdraw herself saying it's getting too late and I can't wait anymore. Then we found something fishy and we said even we don't want to go ahead with this. Please return our money back. He agreed to refund. But till date he is not returning. Some how or the other excuses all the time. Its more than 4 months now. In between he gave us cheque of 3.5 lac as a security cheque saying this is not to be deposited. Cheque is also getting expired soon this month end. All our communication is through what's app chat and voice messages is there as a proof. Kindly help me get my money back. I hv not taken any action yet.