You shot yourself on the leg. Buying and selling of accounts in Bitcointalk is highly prohibited.
Having multiple accounts and account sales are allowed, but account sales are discouraged
At the same time, you have been trick into buying an account. You should know very well that telegram is full of fraud and it will be so easier for an anyone to disguised to be another person.
You also escrow a $500 deal outside the forum, that's poor way of dealing with a stranger.
This might help you in digesting some rules in the forum
Unofficial list of (official) Bitcointalk.org rules, guidelines, FAQ