I'm not sure about the credibility of this site because I never heard of it. However, by simply typing gourl scam on google, you'll see lots of posts stating that this site is scam. Sharing the URL below:

https://www.google.com/m?q=gourl+scam&client=ms-opera-mobile&channel=new&espv=1#sbfbu=1&pi=gourl scam

It's up to you if you want to check each and every post in the results. Personally, I suggest that you stay away from this site especially because you have not been able to withdraw your current balance.