gsammy: I've been getting the same error message as well and I've tried different credit cards and a debit card. Seems to be an error on the site and i've been waiting an entire week to hear back from support. Totally unprofessional
Well I've checked with 2 different banks for 2 different cc cards that were getting the same error on GOG when I tried to fill my GOG Wallet. From what I understand the issue may be GOG's fraud prevention system. The banks have reported no issues on their end.
GOG has straighten the issue out to some people based on some of the forum posts. Seems to be on an individual basis. I am also waiting for my next reply from them.
I think the issue is tied to the user's GOG account based on what I am reading on the forums but I could be wrong. I really hope GOG looks into this as a whole. It really appears to be on their end and maybe some regions. My regeon is US.
Update: Talked to one of my bank's CSR and she said the banks system attempt to communicate with GOG's system failed. At least that's what the bank error code meant according to the CSR. So if I'm unstanding that error correctly, it would seem the bank attempted to transfer or approve the funds to GOG but GOG's system rejected the communication / transaction.