online PDL threats

i took out a loan from an online PDL in late 2010,due to unforseen circumstances i had to close my bank acct. which made the check i had given the PDL to be returned to them unpaid. there was alot going on in my life at the time and honestly i neglected to contact them to make arragements, now i'm getting calls on every day basis from a company by the name of CCS mediations on my cell phone, at work and they've even contacted one of my aquaitances who i haven't talked to in years leaving messages stating that there are charges that have been filed against me for froud for writting a bad check. first, i don't know how they connected people i haven't talked to in years to me or why they would contact them regarding me or my debt, this was emberrasing to say the least, second is this legal? and can they actually file criminal charges against me? i don't mind paying back my debt, but i haven't heard from anyone regarding this and now it's a mediation service or legal office contacting me with threats, isn't there a process to this? what can i do to stop the harrasing calls? i would apreciate any help. thanks