Replacement cancelled without consent & pre-condition and delay in refund.

Dear sir,
I had ordered a samsung galaxy j 8 mobile on 26.07.2018 in exchange offer.The value of it was 18990 rs and in exchange of my redmi note 3 it costed 14360 rs.I got this on 30.07.2018 but due to some defect I requested to replace with new one on 31.07.2018.Replacement request was accepted by technical team of Amazon and it was arrived at my address on 03.08.2018 but courier boy refused to deliver without exchange.Later Amazon cancelled the order without my consent and without any mail of acceptance of cancellation from their end.Later they started refund process on 03.08.2018 and assure me to get refund of exchange value (4630 rs) within 24-48 hrs. in Amazon pay balance and rest amount 14360 rs. within 3-5 working day in my emi card.But sorry to say till today(10.08.2018) no amount of refund has been credited in any of my account.Whenever I talked to customer representatives/Sr. supervisors they all assure me for next 24-48 hrs.Thus they(Amazon team) are mentally and financially harnessing me for my money .I have sent some mails too but got no result.I chatted with their representatives and ask about it (refund and reason of cancellation)but go in vain.I am expecting such a poor and unprofessional service from Amazon.