I sent a parcel to a buyer and she said she never received it so I got on to the Aramex website and it showed it was delivered

I sent a parcel to a buyer and she said she never received it so I got on to the Aramex website and it showed it was delivered. I asked the customer rep for a signed receipt of delivery and she said that she’ll look into it for me but she never got back to me. It is my first time dealing with customer service and it’s the worst ever customer service I’ve ever experienced. I don’t think I will ever use their service again in the future.