Bad service, communication n feedback

Me and my wife had new iPhone n wanted to sell the previous iPhone 13 which was collect since last month and yet no consistent updates n communication, we decided to cancel to offers that didn’t make sense ,which we wer told to pay a delivery fee which was not stated at first as they said the courier was free , received confirmation of cancellation, n paid the amount, hoped they will get back to us , they didn’t, only to receive a WhatsApp message of an offer, but yet we are confused where which stands offer or cancellation