Fiverr HQ is in Israel and there are buyers and sellers from all over the world and a very small number of Fiverr staff. This is not a huge company with a large help desk and it would be very difficult at this stage to have a call center who could manage incoming calls, various languages and accents, etc. While I understand your frustration, Customer Support is clearly working on your issue. (They wouldn’t be trying to help you if they had intended to steal from you.)
As far as your last question, that is an important one. I haven’t seen evidence that the company is not trustworthy but you do have to remember that Fiverr is really just a platform, they don’t sell the services themselves. The platform is for independent sellers to offer services. With anything that is new to you and anonymous, I would suggest starting out cautiously because unfortunately there are always some problem users on any platform. This is also true for Ebay, Etsy and various freelancing sites. Anytime you use any site for the first time I would test it with a smaller amount, perhaps $5-25. I don’t say that because of it getting lost, I haven’t heard of that happening here, but there are other possibilities.
Your bank may have a hold on the funds temporarily because it is an international transaction. Also, if a seller does not deliver what they promise, the ToS tells you that your refund would come in the form of credit to buy other gigs. If you test things out first with a smaller amount of money, you won’t have to panic if something does go temporarily wrong.
Once you find sellers that you are comfortable with and know that things are straightened out with payments, then you would feel safer with higher cost transactions. To me, it’s more common sense than a trust issue. I buy and sell on Fiverr and I start small when I buy from new sellers. I advice my buyers to start small because on a global platform communication isn’t always what we hope. Hang in there and I’m sure you will get more information.