This is not true. There are no international "agreements", laws or regulations that state that deposits have to be returned to the method of deposit. It is entirely up to the sites. They have to have systems in place to prevent money laundering, and there are a number of ways to go about this. I have played on as many sites that don't have that rule (Intercasino to name one), as I have sites that do.
Well, in that case, casinos that explain that they are bound by said agreements when they insist on refunding to the deposit method are LYING.
They are using a bogus "international agreement" or even "international law" to excuse what might be an otherwise unacceptable internal policy that THEY have dreamed up themselves for whatever reason.
The issue of refunds only being allowed to be made to the deposit method have come up often, and the casinos will usually quote variants of this "international law" argument to defend the decision, as well as make it non-negotiable.
There are many complaints about this rule, and it does seem that some casinos go out of their way to make withdrawing as inconvenient as possible, insisting on paying back to initial deposit method when the player asks for something different, yet at the same time REFUSING to pay back to the initial deposit method, as in this case.
If there was really no "hidden agenda" behind these decisions, then there would be consistent application of the policy across the board for all players.
There should be no reason whatsoever (legitimate, that is) for refusing to pay back a player by Neteller if that is the ONLY way they have ever deposited, as no deposit hierarchy is involved, such as refunding old deposits in prefferential order as can be the case where Neteller deposits have been preceeded by card based deposits. Cheque or bank wire withdrawals are meant as a last resort, often used in markets such as the US, or where the player has used cash based or card only deposit methods where refund is impossible.
It seems that MiniVegas are hiding something, either about the particular player, or in general, and are not being truthful in their generalisation that "Neteler is unavailable". It may be more accurate to say "Neteller is not an option we CHOOSE to pay you, even though it is available for other players".
I can say this from experience, as my recent withdrawals from Colosseum and Vegas Poker were paid back through Neteller, my only method of deposit, with no delays. If their excuses were above board, I too should have had a few hitches with Neteller withdrawals with this group, but I have so far had none.
The ONLY way to get any further with this would be to PAB, and lodge a complaint with Neteller about the problems you are having with this merchant, pointing out that the merchant has offloaded the blame to Neteller for the inability to pay by the broad statement that "Neteller is currently unavailable".
The most likely explanation is indeed a shortage of funds in their merchant account, as I have encountered this problem numerous times with other casinos, and when they don't spot this, and attempt the payment, you will see the withdrawal in your Neteller statement, but marked as "Declined" by Neteller, because there is not enough in the merchant account, OR the merchant has exceeded their limits for an individual transaction.
They seem to have plenty in Moneybookers and Click2Pay, however these two eWallets have a worse reputation even than Neteller, and Click2Pay seem unaccountable for their actions, whereas at least Moneybookers has light touch "regulation" from the FSA as does Neteller. Moneybookers, however, ignore emails, and only have very expensive "customer service" at 25p per minute, although a change in the rules by OFCOM have opened a back door for UK players, their 0870 "international" number is now FREE with BT evenings and weekends - on a par with Neteller where it is FREE all the time, thus far easier to persist with a complaint.