when I tried to dial a number I was told I needed to add more minutes. So I phoned speakout and they asked me for a PIN number. I went through all the numbers on my purchase receipt and none of them are a PIN number…

To add airtime all you need to do is call *888 and at the prompt, key in the "Prepaid Card Number" from your airtime receipt.

Phoned the store and the keep telling me I should have a PIN number on a piece of paper which I never received from the store. I only received this receipt.

The cash register should have printed out a voucher at the same time as the sales receipt. This is what mine looked like, with my PIN number (not to be confused with the voicemail system's temporary password, Kira) hidden under the popsicle stick…
Click to see my slip

that number wasn't for voicemail…

It also wasn't the PIN number the service rep was asking for.

Al, they likely wanted the number on the voucher you were supposed to get, so they could verify whether it had already been used in another phone.

Without the number, there's nothing they can do, since they don't know if the voucher was lost, stolen, resold, used, or whatever.

The only way I can think to get the number would be to either have the 7-11 store go back over their sales records and match any voucher being printed with the exact time that your receipt shows you bought the phone (long shot), or see if Ztar's system (the guys that run Speakout) shows a voucher being created at that exact time in that particular store (another long shot).

Either way, treat the vouchers just like cash… either punch them into your account, or put them somewhere safe, like in a safe.