I've faced it last month.

Made the booking in jet website - but could not do OLCI. Called jet and they asked me to enter with MR.

Earlier, I could just enter FirstName, LastName and PNR

yes, but in my case the problem is that I book thru the agent's online booking system myself and most of pax data feeds in automatically..
But still sometimes I get this error and mostly not on the same airline..

Yeah that's exactly what they told me also.. But MR didn't work for me as well. Who knows what's wrong with their systems.

Here's another Jem from Jet Idoits..

I send an email on 20th August regarding some missing miles.. get a response on 22nd Aug saying they have been credited in July (yeah right..!!) I check my account the next day and it is there.. so far so good..

I send another email on 23rd Aug, again for some other missing miles.. The first auto reply i get is - " we can't respond to your email till 20th August. plz bear with us".. (paraphrased)
then I get another auto reply next day- "we are looking into it"..

after 2 weeks of waiting, I wrote to them on 10th Sept, asking about it, and the smug moron replies -"we have already responded to your email on 22nd August. Please see attached response" (paraphrased).. and they have attached a word doc with the response to my first query!! *$#%&^#@&%@$#%

Seriously Jet.. U replied to a query on 22nd August, which I sent to you on 23rd August.. are you guys really that DUMB..!!!!!!!

Try this format:

First Name Section : First Name+Space+MR
Second Name Section: Second Name

I know it's annoying, but that's what worked for me, when I was trying to check in myself and my wife for DEL BRU JFK.. even then when I raeched the airport, I was told we are not checked in, and that's a whole another story..

this is again something new

I had sent them a mail on incorrect credit of bonus miles..
After 2 reminders and couple of weeks , I receive the below..
Its another matter that they have not responded even after I sent the details again replying to the below mail !!

""Dear Mr. XXX

This is with reference to your email dated July 03, 2012. We regret delay in response.

We wish to inform you that we are unable to trace the original email sent by you. Hence may we request you to resend the same for us to check and assist you accordingly.

We regret for the inconvenience caused to you.

Should you require any further information or assistance, please do not hesitate to contact us. Do mention your JetPrivilege number and membership tier in the subject line, in your future correspondence.

Yours sincerely,
For Jet Airways (India) Ltd

xxxxxx
JetPrivilege Service Centre ""

Ah thanks! I was typing "First Name Section : MR+Space+First Name"

be grateful they are not calling you a liar by saying you never sent the mail the first time....

but they have not replied to this mail too.. I hv stopped following up too
So much for JP service !!