Poor Customer services

So our company has an account with FedEx for the pass 15 years but the service we been receiving is extremely poor. Its been three days now of me trying to get hold of our sales rep to assist me in the problems we have. I tried calling emailing with out success. Hope this message reaches someone that can assist me as FedEx is currently costing our business a lot of money they billing us for duties which the receiver must pay the charging us 10x more that the initial quotations we get from them and I'm struggling to get assistant from anyone at FedEx. PLEASE CAN I GET SOME HELP!!!!!