If Gotogate changed your seat without notice, that often happens when the airline reassigns seats due to aircraft changes or load balancing, and as a third-party agency they don’t always update seat selections automatically.
Because seating is controlled by the airline, you usually can’t “restore” your original seat through Gotogate alone.
You must check with the airline directly once your ticket is issued and use their website/app to choose a new seat if allowed by their policy.
To fix it, log into your airline’s manage-booking page with your PNR (the code on your e-ticket) and try to re-select seats there, or ask the airline’s customer service/airport desk at check-in for available options.
If the seat change affected your price or your airline refused the seat you paid for, share your concerns or file a complaint on Xolvie to connect with others and find support.