Aramax slow and delayed

I ordered a package from Shein on the 16th Nov it was sent out a week later. The package was split and I have received the second part which was handled by Buffalo last week the other larger half being handled by Aramax arrived last weekend in the country I paid my tax and it has apparently according to there call centre been sitting at the airport. How can two different companies have two different degrees of service. A parcel I ordered end of Nov has also arrived already through Buffalo. Aramax doesn't care and shows no degree of haste in delivery customers packages. I will continue to phone till I get my package.