20 Slot Pact bags are Not Fixed
https://help.guildwars2.com/anonymous_requests/new
Create a support ticket at the URL above — they should be able to replace your soulbound bag with one that is okay. (If you have the time, you can also use the in-game /bug report tool — that gives the QA team extra data which is usually helpful in troubleshooting issues, although in this case, it’s probably overkill).
Sorry for your trouble and hope that Customer Services responds quickly.
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