Also try nodding your head!! If you shake it from side to side that means yes!! Opposite way round to us!!
Shouldn't imagine you would need to use any more aggressive language though and to be honest most Bulgarians in resort understand simple English like yes, no, please and thank you!
try : blagodaria - thank you
mola - doubles for please & you're welcome
likonosht - goodnight
dovishdonay - goodbye
da - yes
nogodobray - very good
most important of all : vay beeray mola - 2 beers please
excuse the spelling. these taught 2 me by very nice barstaff at the pamporovo hotel