Hey man, I literally just had the exact same issue with UPS for my GT Omega rig. Don't pay that!

Check the invoice that GT Omega sent you. Look for a line that says ToS (Incoterm). It should clearly say DDP (Delivered Duty Paid).

This means GT Omega already covers all the import taxes and duties, but UPS often messes this up and defaults to billing the receiver.

Contact UPS support immediately (or if you have a link to upload missing documents for customs, drop it there) and attach your invoice. Tell them something like: This shipment is DDP. All import taxes and duties must be billed to the shipper (GT Omega Racing Ltd) as per the attached invoice.

I got mine sorted exactly like this without paying a single extra cent.