Xolramu> You can call your credit card company to ask why the charge was blocked. You can also email DUGA and ask. I know your pain; DUGA pretty much features the same studios DMM has plus many more (some smaller studios are not too fond of the latter's 'generous' revenue sharing program).
If what you want is on DUGA, but not DMM, then there's a decent chance it may also be on
http://www.akibacom.jp/ which has a full English site and English-speaking support. They can also do custom orders for titles they don't list. AKIBACOM also has a download site at
https://www.abv.jp but it's Japanese-only and literally feels like you're in AKIHABARA. The design is intense.