Hi,
Alright, before transaction with supplier, the most important thing is to make sure all party (buyer and supplier) agree with :
1. Price.
2. Delivery Time.
3. Payment Terms.
4. Etc.

Now we talk about payment terms.
Buyer ans supplier agreed with Letter of Credit as payment method.
Both parties must agree with LC draft before issue, then buyer open LC through his bank (Issuing Bank), it must Irrevocable LC
(about Irrevocable LC, please my other article in this forum)
If anything happen with supplier, your money still safe, just lost small amount, rather than got scam, you will lost total money you gave.
Letter of Credit is very recommended payment method during cross country transaction.

And now, How to solve the problem.
Before decided supplier, there would be wise ask someone in supplier country, how supplier capacity and capabilities.
You can ask or hire Inspection service in suppliers country to audit supplier / supplier verifications.
Inspections method will show you a report mention:
1. Who they are - This is to avoid scam, are supplier real or fake.
2. How big their manufacture - To show you how real supplier.
3. How much production capacity - To show you what equipment could make their product quantity.
4. Product Quality - To show you their quality to meet your requirement.

So, when you feel satisfy with supplier had been verified results then you can place an order with them.
You can go to ask for detail about best price offered, delivery and payment method.
In your case, I think your suppliers bank doesn't have Advising Bank.
So it will take a time to receive any instruction from Issuing Bank goes to Beneficiary Bank.

Missing Link
This is a life, anything could happen, you should check supplier for detail before you go, the bad think is you just believe from their fabulous suppliers website and their speech to attract you and place an order without knowing first.

Open Mind
Now you lost your money for bank charges and lost your time.
My best advise is spend small amount of USD to hire Inspection Service in Suppliers country, to safe you from Fraud Business and Scam. Rather than lost your money (for bank charges or got scam) and most very valuable is lost your time.

In Your Case
Your supplier doesn't have any Capacity, you can see how product ready to be deliver.
Your supplier doesn't have any Capabilities, you can see from his investment (how much money to cover productions progress)
Your supplier aren't PRO at all, you can see how they ask you to revise the price, they should think about that, in case if any happen.

I hope you will be OK and still exist with your trades.

Alright Guys, be a Wise and

life is like a drama.We should keep clear head to guide ,in that way any one can not cheat us successful.
And please search much information about your supplier before doing a business.To see it is realible or not.