I haven't read the whole thread, so apologies if this has already been said, but the only people entitled to sit in "my own seat" are the people who purchased a private seat license for 1st team home games subject to the terms and conditions.
Most people have purchased a season ticket to sit in...
If you want to try a seat in the Upper tier, you could ask the club to transfer your seat for the Swansea home match. You don't have to wait for a cup tie to try a different seat.