Problem with Virgin ISP proxy

I bought an ISP proxy and configured it but there's a weird problem that I couldn't find on Google

I can access only a few from the most famous websites like Google, Facebook, and Amazon,
but I can never access any other website,

I tried 2 devices and the same problem happens
I contacted the support they don't know anything and sent me a screenshot showing that the proxy works with all of the websites

Some proxy providers restrict the websites that you can visit. If that's not that case, then your IP could be blacklisted. You should contact the proxy provider and discuss this issue further with them or request an exchange.

ristoriel said:

Some proxy providers restrict the websites that you can visit. If that's not that case, then your IP could be blacklisted. You should contact the proxy provider and discuss this issue further with them or request an exchange.

Click to expand...

I found out that the problem is from my ISP,
I tried it in my friend's PC which is in another governerate (State) and the same thing happened

I used a vps and installed Ubuntu to use it as RDP and tested the proxy there and it works perfectly