I gad some play in my crank and so I brought it in to my LBS. I also had chain hop and a new chain didn't fix it so I had them swap in a new rear cog. I had asked them to 'service" my crank and mentioned grease. When I picked it up they said all it needed was to be tightened. I rode it 5 miles and it is making God-aweful clanking sounds and is loose again. (btw - it was fine when I test rod eit outside the shop)

what the heck is clanking?
do I take it back to this shop or go to another?