Ecom Express — Mobile delivery issue

I ordered 2 mobiles from flipkart with exchange, exchange : one mobile is redmi y2 another is redmi 6 pro, and ordered Infinix Smart 7 * 2 from flipkart in exchange of them, Now issue is, on 6h october, 2023 courier partner came to deliver mobile whose mobile number is [protected]. They checked my old mobies for exchange, accepted redmi y2 whose exchange value is 1050 and rejected redmi 6 pro, whose exchange value is 2050. I total believed that and ready to take both mobiles, and giving cash for rejected mobile. They opened package, and scanned new mobile, and then told me that he got server error. So can't deliver mobile, gave me personal mobile number of him and told me to call him after an hour. I called him after an hour, he told me that he will check and call back, still I wont receive any call from him, so that I call him on next day on 7th october, he told that come to my office after some time. so he will give mobile on his office, as he is able to solve error on his office only. But we don;t have time to go there on saturday so we won;t. Now we call him on monday after 2 days. till then I daily got message of out for delivery, but not receive any call from delivery agent. On monday he told me that due to rush he has not time to deliver on door step, come to office and collect, on tuesaday I go there. They from 2 old mobiles, he scanned vice verca and rejected redmi y2 which we already accepted on first delivery, and told me to give money of that, I asked him questions but he told give otp fast as already other customers are waiting for delivery. I gave otp and checked, they delivered rejected mobile's exchange to me, and give me one mobile, he scan for another and told that still it is some issue, come tomorrow. I went today, waited for 2 hours there. and still same answer. already went there for 3 times for delievery, and at their office I have seen that many customers like me are harassed like me like this. He is rejecting everyone's mobile, and told every customer on call to come there, and so everyone are coming to take parcel from their office, I think courier boy is very lazy to deliver it. They are not cancelling mobile as well not giving us, please solve my complaint ASAP. If they are providing door step delivery then they must do that. Hence, we went there 3 times but still it is not delivered to us.