I tried to lift the base on mine at the weekend but couldn't budge it - looking at a photo of 1 on ebay it looks like a metal frame same as on most cars that should lift up ?
If you figure it out please let me know
try this ill try in morning put hand front of seat near there door push into the middle till you stop think there will be bracket there then other hand from middle towards your other hand and then lift up
Removing the rear seat base in the current model Ibiza is probably the same as it is in the current model Polo As they’re essentially the same car under the skin. This YouTube video shows the process for the Polo;