I have never had any trouble withdrawing from Hashnest and have been with them for a long time. I mine LTC and BTC with them. On one occasion their wallet was under maintenance due to a possible security breach but that was resolved quickly and a global msg was sent out to all users.

I cannot comment on their response times when asking them questions as I have never had too. I know in some countries there is a restriction on the use of cryptocurrencies so perhaps people with this trouble are from there? Your IP address would determine this and it's not unheard of with some Exchanges.

Maybe the amount I withdraw from mining has an effect on the fee paid thus the time it takes for me to receive my funds. I do not know if small withdrawals would mean a low fee therefore a long time to confirm.

If your withdrawal says it has taken place yet you have not received your funds, one can try viabtc accelerator https://pool.viabtc.com/tools/txaccelerator/ and enter you tx ID. There are tx fee limits  but once through it should be processed in the next block.

Im hoping to help here, maybe I'm not but good luck getting your funds.