ZurichLady,
Exact same thing happened to me. That was (one of ) the reasons that brought me here. Some advice from another noob w/out boobs,
(take FREE advice for what it's worth), When you were asked to go thru the process of buying the BTC, there's a screen that asks for a PIN but there's no indication that you should keep the PIN, ie. no explanation as to why you're giving the PIN. It's presented as just "input a PIN".
I went thru the process you're describing in your post,
"....I asked support at Bitinstant (kinda cool company) and they forwarded the ticket to Coinapult who said I had to put a ticket in at Bitinstant! So we could go in circles forF'never.) and found Bitinstant was willing to help in anyway they can but Coinapult is less than useless. The never acknowledged they had even received the service request.
I had to go thru the process of buying another BTC and found the screen where they asked for the PIN and I remembered I had used a throw-away PIN (one I use for hotel room keys, casino card PINS, etc). If you'll go thru the process again (only to the point where they ask for the PIN) you may remember what you used. If you have a bank account, s/up an account w/Blockchain ( @---
https://blockchain.info/wallet/----) they are good in that they will s/up a wallet and facilitate purchase of BTC, that you can then "send" to another "wallet" etc., etc., etc.
I also had some problem with "MultiBit" wallet client. But that's another story entirely.
Hope you get your money (BTC), but if you can't remember the PIN you used, I"m afraid you 'll be out of luck, and out your money too. If there's any way I can help please PM back and I''ll help if I can.