where can you request a refund of a decree issued by former minister Dirk Van Mechelen?

Answer

Best,

Decrees of the Flemish government are published in the Belgian Official Gazette. This can be consulted online for legislation from 1994. Older copies can be found in libraries.
A consolidated version of legislation (version of the legislation with all amendments) is available via Justel. It also includes a part of legislation from before 1994.

The Flemish government also has its own database of legislation, De Vlaamse Codex, with consolidated (merged) Flemish legislation since 1/1/1970.

I’ve added the links to the database search engine.

Sincerely,

Junior Burssens