unknown debt from control account

[Bukola]

i newly moved in to the UK this year February 2023 , i had an excess luggage at the airport , after few month of settling down i told my grandfather to send my remaining stuffs through carrier delivery which was sent through fedex, i was told to pay 96 pound as they have calculated my stuff (6kg) which i paid,5 days later i received my parcel,3 weeks later i received an invoice by post that am owing fedex 106 pounds, i contacted immediately and i was been reffered from one customer service to another till i received an email to forward my query to fedexquery department which i did not reply until last week my flatmate in my formal apartment told me i have a post,i insisted for her to open and it was from control account(debtor collector) that i need to pay them that their customer(fedex) said am owing them. i called the contact on the letter to explain am not owning them i paid in full before i received my parcel with their explanation i was told that i will pay customer since am a business owner,(6kg) stuff business owner how, i got a job offer as a carer and the home brought me to uk, i sent the list of items in the parcel sent that it is my used stuffs the only things that is new there is my skincare.Pls advice me on what to do ,all this drama from them is making me break down.thanks.