Subj. Without actual trading pairs on exchanges, for example I want to sell ARK when its under 3$ on bittrex (There is no ARK/USDT pair). Its two operations:

1. Sell for BTC
2. Buy USDT with BTC

I can't setup this to be done automatically. Any services or scripts allowing me to do this? Coinigy? TradingView? Or some crypto dashboards?