Not a PIVX problem. Yobit is notorious for failing to update wallets (not just for PIVX). All PIVX or any other coin can do is remind them. Your coins are stuck there until Yobit gets off its ass, which may or may not ever happen. Sorry.
More generally, use Yobit only if you absolutely have to. Cryptopia caters to a similar demographic (i.e., they list pretty much any coin that wants to be listed) but is far less shit. But for something pretty established and 'mainstream' like PIVX, better to use a reputable exchange regardless. Bittrex is usually a safe choice.